Field

[0001 ] The present disclosure relates to building blocks and building block assemblies.

Background

[0002] Modular and interconnectible building blocks for construction of toys, such as toy figures, toy vehicles, toy houses, toy farms, toy machines, toy models, and other toy assemblies, toy products and toy structures are known and have been recognized for their educational values, for example, in promoting and encouraging creativity, patience and perseverance. Modular and interconnectible toy building blocks are advantageous, for example, many different types of toy assemblies, toy products and toy structures can be built with a small number of well-designed building blocks of basic configurations and the building blocks can be re-used for building of other toy assemblies, toy products and toy structures. Modular and interconnectible building blocks are also used in building industries, for example, as modular components for construction of buildings and structures. Use of modular and interconnectible building blocks has been known to facilitate flexible, expeditious and standardized construction with less manual work requirements and promote productivity. In addition to application as toys and in the building industry, modular and interconnectible toy building blocks are also used for modular construction of tools, equipment, appliances, and many other types of products.

Disclosure

[0003] Modular and inter-connectible building blocks and assemblies comprising modular and interconnectible are disclosed.

[0004] A building block according to the disclosure comprises a plurality of connection portions. Each connection portion has a center axis which defines a coupling axis and a coupling direction, and the connection portions are connected in series and distributed along a distribution axis which is formed by joining the center axes or coupling axes of the plurality of connection portions connected in series and which defines a distribution direction. Each connection portion comprises an engagement portion, the engagement portion comprising mechanical snap-fit mating features which define an engagement surface in the form of a snap-fit mating surface for making snap-fit engagement with a matched counterpart connector of a counterpart building block along the coupling direction. The engagement portion is delimited between a first plane which extends in a lateral direction which orthogonal to the center axis and a second plane which is parallel to the first plane and axially displaced in the coupling direction.

[0005] In some embodiments, the engagement portions of adjacent connection portions are in abutment and the snap-fit mating surfaces of adjacent engagement portions are in abutment and cooperate to form a rippled portion, the rippled portion extending about the coupling axis in a peripheral direction orthogonal to the coupling direction to form a peripherally extending indentation or a peripherally extending protrusion which extends in a direction orthogonal to the coupling direction. The peripheral indentation is in the shape of a notch having a rippled profile or a wavy profile in the coupling direction and/or a tapered profile which tapers to narrow towards the coupling axis. The peripheral protrusion has the shape of a tapered teeth which narrow towards the coupling axis.

[0006] In some embodiments, the peripherally extending indentation or the peripherally extending protrusion is defined by cooperation of a first engagement portion of a first connection portion and a second engagement portion of second connection portion, the first connection portion and the second connection portion forming the pair of adjacent connection portions.

[0007] In some embodiments, the rippled portion or a portion thereof comprises a curved portion which follows a concave curvature or a convex curvature.

[0008] In some embodiments, the engagement portions of the plurality of connection connections cooperate to define a rippled surface, the rippled surface comprising a plurality of ripped portions each of which is in the shape of a tapered notch having a rippled profile or a wavy profile in the coupling direction and/or a tapered profile which tapers to narrow towards the coupling axis, and each rippled portion extends in a plane which is orthogonal to the coupling direction to form a peripherally extending indentation.

[0009] In some embodiments, the snap-fit mating surface extends around a periphery of the building block and extends along the coupling direction between the first plane and the second plane to define an engagement plane which is orthogonal to the coupling direction. The snap-fit mating features of the plurality of connection portions are connected in series to form a series of rippled portions comprising a plurality of ripple or rippled portions connected in series.

[0010] In some embodiments, adjacent ripple portions forming the series of rippled portions are continuous or in abutment, and/or are identical. [001 1 ] In some embodiments, the center axes of immediately adjacent connection portions of the plurality of connection portions are aligned along a common center axis or intersect within the building block.

[0012] In some embodiments, the building block comprises a main body or a main housing and an internal bore which is formed inside the main body or the main housing and having a bore defining surface. The plurality of connection portions comprises a plurality of internal connection portions which is formed inside the main body or the main housing, and the engagement portions of the plurality of internal connection portions are inside the main body or the main housing and are distributed in series to define the internal bore or part thereof. The internal bore has a bore axis which is coaxial with the distribution axis of the plurality of internal connection portions.

[0013] In some embodiments, the internal bore is a through bore extending through opposite sides of the main housing.

[0014] In some embodiments, the plurality of connection portions further comprises a plurality of external connection portions and the plurality of external connection portions surrounds the internal bore.

[0015] In some embodiments, the bore axis and the distribution axis of the plurality of external connection portions are coaxial.

[0016] In some embodiments, the distribution axis is orthogonal to the coupling axis.

[0017] In some embodiments, the building block comprises an elongate member having a longitudinal axis and the connection portions are distributed along the longitudinal axis. The coupling axis being orthogonal to or at an acute angle to the longitudinal axis.

[0018] In some embodiments, the elongate member has a thickness and/or a width comparable to or slightly larger than the thickness of the connection portion, the thickness being measured in the coupling direction and the width being measured in a direction orthogonal to the coupling direction and the distribution axis.

[0019] A building block assembly disclosed herein comprises a plurality of building blocks in snap engagement. The plurality of building blocks comprises a first building block and a second building block which are snap joined to form a snap joint, the snap joint being a pivotal joint defining a pivotal axis. The first building block comprises one first connection portion or a plurality of first connection portions (male) which are distributed along a first distribution axis, and the second building block comprises one second connection portion or a plurality of second connection portions (female). The first connection portion has a first engagement portion having a first coupling axis and the second connection portion has a second engagement portion having a second coupling axis. The first engagement portion and the second engagement portion are a pair of matched engagement portions that can be snap joined, and the first building block and the second building block which are pivotally joined so that the first building block and the second building block are relatively rotatable about the pivotal axis which is coaxial with both the first coupling axis and the second coupling axis. The first building block and the second building block are building blocks according to the disclosure.

[0020] In some embodiments, the first building block comprises a main body.

[0021 ] In some embodiments, the building block assembly is a chain assembly or a rotor blade assembly comprising a rotor blade mounted on a rotor shaft.

[0022] In some embodiments, the first engagement portion and the second engagement portion are matched and compatible connectors having matched dimensions and opposite or complementary mating properties.

[0023] In some embodiments, the engagement portion is shaped, profiled and dimensioned to define a snap engagement plane which is orthogonal to the coupling axis or which is confined to within an angle of between 75 degrees and 105 degrees to the center axis.

[0024] In some embodiments, the plurality of connection portions comprises a plurality of external connection portions, and each connection portion comprises a protruding portion which projects radially away from a main body for a radial extent and which extends about center axis to surround the main body. The radial extent gradually diminishes as the protruding portion extends towards the first plane and/or the second plane so that a notch is formed between an immediately adjacent pair of abutting connection portions.

[0025] A building block herein comprises one or a plurality of connectors to facilitate detachable or releasable mechanical connection between modular building blocks in abutment. The mechanical connection is typically by press-fitting or snap-fitting. The building block comprises one connector or a plurality of connectors on at least one connection surface and building blocks can be stacked with their respective connection surfaces in abutment connect and the connectors on their respective connection surfaces in detachable mechanical engagement.

[0026] A building block herein may be a toy building block. A toy building block is typically made of thermoplastics such as ABS (acrylonitrile butadiene styrene), PC (polycarbonate), or other plastic materials that a high degree of strength and rigidity, as well as a small degree of resilience to be slightly resiliently deformable to facilitate press-fit or snap-fit engagement. [0027] A building block herein may be made of clay, ceramic, porcelain, concrete, or other mouldable materials that have a high rigidity and a very low degree of resilience or virtually no resilience.

[0028] A building block herein may also be made of wood, metals, for example, steel, aluminum, aluminum alloys, or other materials that can be shaped.

[0029] Where a building block is made of a material having a high rigidity with a very low degree of resilience or no resilience, the building block may connect with a building block having a sufficient degree of resilience to facilitate mechanical connection by resilient deformation of the connector(s) thereon.

[0030] In general, a building blocks can be rigid and slightly resilient or non-resilient, and the rigidity and resilience may be selected to suit applications by selecting appropriate materials or appropriate mix of materials.

[0031 ] A building block herein may be ceramic building block or a porcelain building block. The ceramic or porcelain building block may be in the form of a ceramic brick or a porcelain brick, a ceramic tile or a porcelain tile, a ceramic panel or a porcelain panel, or other forms of ceramic parts or porcelain parts without loss of generality. The ceramic or porcelain building blocks may be interconnected using binding agents such as glue, cement, or mortar to form the modules, assemblies or sub-assemblies, or interconnect wit building blocks made of a rigid and slightly resilient material.

[0032] A building block herein typically comprises a main body, a first surface on a first side of the main body, a second surface on a second side of the main body, a peripheral portion extending between the first surface and the second surface, and a plurality of connectors formed on the main body. The main body is typically rigid or semi-rigid and the connectors have peripheral walls which are rigid or semi-rigid and having a small degree of resilience to facilitate snap engagement with corresponding connector through resilient deformation of the engagement portions of the connectors. The connectors are usually formed on a panel portion of the main body. In some embodiments, male connectors are formed on one panel portion and female connectors are formed on another panel portion separate from the panel portion on which the male connectors are formed. In some embodiments, male connectors and female connectors are formed on a common panel portion.

[0033] A connector herein means a building block connector unless the context requires otherwise. A building block connector comprises a connection portion having a coupling axis defining a coupling direction. The connection portion comprises an engagement portion for making closely fitted engagement with a matched connector portion of a matched connector to form a pair of engaged connectors.

[0034] An engagement portion comprises mechanical mating features for making closely fitted engagement with a corresponding engagement portion of a matched connector to form a pair of engaged engagement portions. An engagement portion may be a male engagement portion or a female engagement portion.

[0035] A connector is generally classified as a male connector or a female connector. However, a male connector may comprise a female engagement portion in addition to its inherent male engagement portion and a female connector may comprise a male engagement portion in addition to its inherent female engagement portion.

[0036] A male engagement portion comprises male mating features. A male engagement portion typically comprises a protrusion which is shaped and sized for closely-fitted reception of a corresponding female engagement portion. A protrusion adapted for closely-fitted reception of a corresponding female engagement portion is a matched corresponding male engagement portion of that corresponding female engagement portion. A protrusion herein is also referred to as a "protrusion portion", a "protruding member", a "protrusion member", "protrusion body", and "protruding body" and the terms are interchangeably used herein unless the context requires otherwise.

[0037] A female engagement portion comprises female mating features. A female engagement portion typically comprises a coupling receptacle which is shaped and sized for closely-fitted reception of a corresponding male engagement portion. A coupling receptacle adapted for closely- fitted reception of a corresponding male engagement portion is a matched corresponding female engagement portion of that corresponding male engagement portion. A receptacle herein means a coupling receptacle of a female building block connector unless the context requires otherwise. A coupling receptacle of a female building block connector is also referred to as a male engagement portion receptacle or a male-connector receptacle.

[0038] A pair of connectors having matched corresponding engagement portions when on separate building blocks are detachably engageable to form a releasable mechanical connection. When the pair of connectors have matched snap engagement portions, the connectors are snap engageable to form a snap engaged connector pair. [0039] A male engagement portion and a corresponding female engagement portion having matched and compatible mating features will enter into closely fitted engagement when they are brought or moved relatively towards each other with their respective coupling axes aligned and press connected along the aligned coupling axes. The fitted or closely fitted engagement herein may be by interference fit or snap fit. When a pair of matched connectors herein are brought or moved relatively towards each other with their respective coupling axes aligned and then pressed together, the matched connectors will engage and enter into closely fitted engagement.

[0040] A connector has a characteristic radial profile. The radial profile of a connector is characterized by the radial extent of the engagement portion or the engagement portions of the connector between its axial ends. A snap connector is characterized by a non-uniform radial extent in the axial direction, and more particularly by a bulged radial profile.

[0041 ] A male connection portion comprises a protruding portion which is to enter into a receptacle of a corresponding female connection portion to make releasable mechanical engagement therewith. The protrusion portion may be in the form of a protrusion body, a protruding body, a protrusion member or a protruding member.

[0042] The protrusion portion of a male connection portion projects from a base surface and extends in an axial direction away from the base surface, the axial direction being with respect to the coupling axis of the protrusion portion. A male connection portion comprises a connector head defining its axial end. The axial extent of a protrusion portion, measured along the coupling axis of the male connection portion between the base surface from which it projects and its axial end, defines the height of the protrusion. The protruding body has an outer peripheral wall which defines the mating features of the protrusion portion, including shape, configuration, radial profile and dimensions.

[0043] The protrusion portion of a male snap connector has a radial profile which is defined by its outer peripheral wall. The radial profile of a snap connector is characterized by a non-uniform radial extent in the axial direction. A male snap connector typically comprises a bulged portion having a bulged radial profile and a reduced portion having a reduced radial profile.

[0044] A typical protrusion portion herein is an annular protrusion comprising a first protrusion portion and a second protrusion portion. The first protrusion portion and the second protrusion portion are in series and are aligned on the coupling axis. The first protrusion portion is in abutment with the base surface and the second protrusion portion comprises the axial end, which is usually a free axial end. The first protrusion portion is, in the axial direction, or axially, intermediate the second protrusion portion and the base surface. [0045] The first protrusion portion is referred to as a neck portion which is supported on the base surface and the second protrusion portion is referred to as a head portion which is supported by the neck portion.

[0046] The head portion has an enlarged radial profile compared to the neck portion radial profile, and is also referred to as an enlarged portion. As the profile enlargement is in the radial direction, the head portion is also referred to as a widened portion.

[0047] In general, the head portion is an enlarged portion having a head portion radial profile which is a bulged radial profile, or a bulged profile in short.

[0048] The head portion has an outer periphery which is in the general form of a peripherally extending rib. A peripherally extending rib herein is an annular rib having the radial profile of the head portion radial profile in the peripheral direction. The annular rib is defined by the outer peripheral wall of the protrusion portion and may be continuous or non-continuous. The peripheral direction is orthogonal to the coupling axis and is a tangential direction to a circle defining the annular rib. The annular rib surrounds a core portion of the head portion, and the core portion of the head portion may be solid or hollow. When the core portion is hollow, the head portion is in the form of a hollow shell having an internal compartment. The head portion radial profile and the annular rib has the radial profile of a radial protrusion and defines an engagement portion, and more specifically, defines a male snap engagement portion of a male connection portion. The engagement portion on the head portion of a male connection portion is referred to as a first engagement portion or a first snap engagement portion of the protrusion portion or of the male connection portion for ease of reference. The terms "rib" and "ridge" are equivalent and are used interchangeably herein.

[0049] The bulged head portion has a maximum radial extent defining a maximum radial plane at an axial level with respect to the base surface. The maximum radial plane is a maximum transversal plane, and the axial level of the maximum radial plane is a maximum radial extent level.

[0050] The bulged portion has a lower surface which extends between the maximum radial plane and the base surface. The lower surface is a tapered surface which oppositely faces the base surface. The radial extent of the lower surface of the bulged head portion at an axial level decreases as the axial level moves closer towards the base level of the base surface to define a lower tapered surface. Conversely, the radial extent of the lower surface of the bulged head portion at an axial level increases as the axial level of the lower surface away from the base surface increases. The radial extent of the lower surface of the bulged head portion reaches a local minimum at an axial level where it joins the neck portion.

[0051 ] The head portion tapers to narrow as it extends axially from the maximum radial extent plane towards the base surface. Conversely, the head portion flares to widen as it extends axially from the base surface towards the maximum radial extent plane.

[0052] The axial free end of the head portion may be flat or rounded. Where the axial free end is flat, the male connector has a flat head. Where the axial end is rounded, the male connector has a rounded head. The rounded head may be in the shape of a dome, a spherical cap, or a rounded boss or other suitable shapes.

[0053] The head portion radial profile extends in a peripheral direction to define an annular outer periphery of the head portion and the neck portion radial profile extends in a peripheral direction to define an annular outer periphery of the neck portion.

[0054] The neck portion has reduced radial profile compared to the head portion radial profile, and is also referred to as a reduced portion. As the profile reduction is in the radial direction, the neck portion is also referred to as a narrowed portion.

[0055] In general, the neck portion is a reduced enlarged portion having a neck portion radial profile which is a tapered radial profile, or a tapered profile in short.

[0056] The neck portion has an outer periphery which is in the form of a peripherally extending channel. The peripherally extending channel is an annular channel having the radial profile of the neck portion radial profile in the peripheral direction. The annular channel is defined by the outer peripheral wall of the protrusion portion and may be continuous or non-continuous. The peripheral direction is orthogonal to the coupling axis and is a tangential direction to a circle defining the annular channel. The annular channel, that is, the peripherally extending channel, surrounds a core portion of the neck portion, and the core portion of the neck portion may be solid or hollow. When the core portion is hollow, the neck portion is in the form of a hollow shell having an internal compartment. The neck portion radial profile and the annular channel has the radial profile of a radial indentation and defines an engagement portion, and more specifically, a female snap engagement portion on a male connection portion. The engagement portion on the neck portion of a male connection portion is referred to as a second engagement portion or a second snap engagement portion of the protrusion portion or of the male connection portion for ease of reference. This second engagement portion is a retention portion which is adapted to receive and retain a neck receptacle portion of a female connector. The terms "channel" and "groove" are equivalent and are used interchangeably herein.

[0057] The neck portion has a local maximum radial extent at an axial level where it joins or is in abutment with the head portion. The local maximum radial extent defines a local maximum radial plane, which is also a local maximum transversal plane.

[0058] The neck portion has an outer peripheral surface which extends between the local maximum radial plane and the base surface. The outer peripheral surface is a tapered surface which oppositely faces the base surface. The radial extent of the outer peripheral surface of the neck portion at an axial level decreases as the axial level moves closer towards the base level of the base surface to define a tapered outer peripheral surface. Conversely, the radial extent of the outer peripheral surface of the narrowed neck portion at an axial level increases as the axial level of the outer peripheral surface away from the base surface increases. The radial extent of the outer peripheral surface of the neck portion reaches a local minimum at an axial level where it joins the head portion. The outer peripheral surface is optionally a smooth continuation of the lower surface of the head portion. Where the lower surface of the head portion follows a curved profile to taper, the radial profile of the outer peripheral surface may follow a curved profile which is a curved continuation of the curved profile to taper. In some embodiments, the curved profile follows a radius of curvature equal to half the maximum radial extent.

[0059] Therefore, the neck portion tapers to narrow as it extends axially from the local maximum radial extent plane towards the base surface. Conversely, the neck portion flares to widen as it extends axially from the base surface towards the local maximum radial extent plane.

[0060] While the peripheral channel is primarily defined by the outer peripheral surface of the neck portion in cooperation with the base surface, the entire channel may be regarded as being defined by the lower axial end of the enlarged portion, the narrowed neck portion and the base surface in cooperation.

[0061 ] The channel may have a constant radial extent in the axial direction or may have a tapered radial profile such that the radial extent of the neck portion decreases as its axial level decreases towards the base surface.

[0062] The tapering may follow a curved profile, for example the profile of a convex curve, a straight slope or other desired profiles without loss of generality.

[0063] In general, the axial extent of a protrusion of a connection portion is a fraction of the maximum radial extent of the protrusion, and the fraction is optionally between 20% and 80%, for example, in percentage terms, at 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, or any range or ranges defined by a combination of any of the aforesaid values and/or ranges. Typically, the axial extent will be in the higher range of between 50% and 80% where the protrusion has a rounded end or partial spherical end and in the lower range of 15% and 60% where the protrusion has a flat head or flat axial end. For an annular protrusion, the maximum radial extent E is the diameter D of a circle, the circle defines a maximum radial extent plane and the aforesaid fraction is also in respect of the diameter.

[0064] The axial extent between the maximum radial extent level and the axial free end of the protrusion portion is a fraction of the maximum radial extent of the protrusion, and the fraction is optionally between 5% and 50% of the maximum radial extent, E, at the maximum radial extent level, for example, in percentage terms, at 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, or a range or any ranges formed by a combination of any of the aforesaid values as limits of a range or limits of ranges. This axial extent of the upper portion of the protrusion will be in the lower range of between 5% and 30% where the protrusion has a flat head or flat axial end, and in the higher range of between 25% and 50% where the protrusion has a rounded end or partial spherical end. When the axial extent of the upper protrusion is 50%, the upper portion has a hemispherical shape.

[0065] The axial extent between the base surface and the maximum radial extent plane of the protrusion is a fraction of the maximum radial extent of the protrusion, and the fraction is optionally between 6% and 30% of the maximum radial extent, E, for example, in percentage terms, at 6, 8, 10, 12, 15, 18, 20, 25, 30, or a range or any ranges formed by a combination of any of the aforesaid values as limits of a range or limits of ranges.

[0066] The axial extent of the bulged portion is a fraction of the maximum radial extent of the protrusion, and the fraction is optionally between 5% and 25% of the maximum radial extent, E for example, in percentage terms, at 5, 10, 15, 20, 25, or a range or any ranges formed by a combination of any of the aforesaid values as limits of a range or limits of ranges.

[0067] The axial extent of the neck portion is a fraction of the maximum radial extent of the protrusion, and the fraction is optionally between 5% and 15% of the maximum radial extent, E for example, in percentage terms, at 5, 10, 15, or a range or any ranges formed by a combination of any of the aforesaid values as limits of a range or limits of ranges.

[0068] The radial extent of the neck portion is a fraction of the maximum radial extent of the protrusion, and the fraction is optionally between 90% and 99% of the maximum radial extent, for example, in percentage terms, at 90, 91 , 92, 93, 94, 95, 96, 97, 98, 99, or a range or any ranges formed by a combination of any of the aforesaid values as limits of a range or limits of ranges. [0069] The radial extent of the radial indentation defining the channel of the neck portion is a fraction of the maximum radial extent of the protrusion, and the fraction is optionally between 1 % and 6%, for example, in percentage terms, at 1 , 2, 3, 4, 5, 6 or more, or a range or any ranges formed by a combination of any of the aforesaid values as limits of a range or limits of ranges.

[0070] The protrusion portion or a portion thereof may be a convex annular portion which follows a convex curvature as it extends towards the base surface in the direction of the coupling axis. The convex annular portion may have the shape of a spherical segment having a radius of curvature R, where R is half the value of the maximum radial extent of the maximum radial plane, and an axial extent or height h. The maximum radial plane is usually contained between two smaller radial planes so that the radial extent of the convexly curved portion increases from a first radial extent defined by a first smaller radial plane to the maximum radial extent and then decreases to a second radial extent defined by a second smaller radial plane as the curved portion extends along the direction of the coupling axis, the radial plane extending in a transversal direction or a lateral direction which is orthogonal to the coupling axis.

[0071 ] The protrusion portion between the base surface and the maximum radial plane may be in the shape of a spherical segment or a truncated cone, i.e., frusto-cone. The axial height between the base surface and the maximum radial plane is optionally between 20% and 85% of R, where R is the radius of the sphere defining the spherical segment, for example, in percentage terms, at 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, or a range or any ranges formed by a combination of any of the aforesaid values as limits of a range or limits of ranges.

[0072] Where the neck portion of the protrusion portion in abutment with the base surface is in the shape of a spherical segment, the neck portion has a shape of a lower spherical segment and has a convexly curved profile in the radial direction. When the neck portion is so shaped, the neck portion has a smaller radial extent at the base surface and a local maximum radial extent at an axial separation from the base surface.

[0073] The radial extent of the neck portion at the base surface is at a fraction of the maximum radial extent, and the fraction is optionally between 90% and 98.8%, for example, in percentage terms, at 90, 92, 94, 96, 98, 98.8, or a range or any ranges formed by a combination of any of the aforesaid values as limits of a range or limits of ranges.

[0074] The local maximum radial plane is elevated above the base surface and a radial plane having a smaller radial extent is in abutment with the base surface. [0075] The neck portion may taper to join the base surface and joins at a joining angle. The tapering may follow a convexly curved profile, may have a constant slope, or other desired tapering manner. The joining angle is an acute angle which is optionally between 50 degrees and 88 degrees, for example, in degree terms, 50, 55, 60, 65, 70, 75, 70, 80, 85, 88, or a range or any ranges defined by a combination of any of the aforesaid values and/or ranges.

[0076] The protrusion portion, for example, the bulged portion or the reduced portion, may comprise a cylindrical body or a prismatic body which projects away from the base surface, with a tapered portion formed at a peripheral region in abutment with or in proximity to the base surface.

[0077] A snap connector or the engagement portion of a snap connector herein is axis- symmetrical. An axis symmetrical engagement portion has axis-symmetrical mating feature profiles. An axis-symmetrical engagement portion or connector typically has a circular cross section at an axial defined by the coupling axis of the engagement portion or the connector. In some embodiments, the engagement portion may not be exactly axis-symmetrical but has a square cross-section or a cross-section of a regular polygon having five side, six sides, seven sides, eight side, nine sides, ten side or more. A snap connector herein includes both the axis- symmetrical and non-axis-symmetrical types unless the context requires otherwise.

[0078] On the other hand, the radial extent of a protrusion portion of a press-fit or interference-fit connector without snap-fit features is substantially uniform in the axial direction.

[0079] A female connection portion comprises a coupling receptacle for reception of a protrusion portion of a corresponding male connector. More specifically, a female connection portion comprises a coupling receptacle, or receptacle in short, for closely-fitted reception of a protrusion portion of a corresponding male connection portion to facilitate snap engagement. When a male engagement portion is in closely fitted engagement with a female engagement portion, the male engagement portion is received by the receptacle and at least a portion of the male engagement portion projects into and is received inside the receptacle compartment.

[0080] The receptacle of a female connector comprises a receptacle compartment and a receptacle entry through which an axial end of a protrusion of a corresponding male connection portion is to enter the receptacle compartment. The receptacle comprises an inner peripheral wall which defines the receptacle compartment, the receptacle entry, as well as a receptacle entry plane and an entry aperture at the receptacle entry. The entry aperture is typically on an axial end of the receptacle and is also referred to as an access aperture and the receptacle entry plane is orthogonal to the coupling axis. The entry aperture defines a minimum radial clearance of the receptacle which in turn defines a maximum radial extent of the protrusion or the bulged portion of a protrusion that can enter into the receptacle without radial deformation of the receptacle entry or the male connector protrusion. The coupling receptacle extends in the axial direction away from the receptacle entry to define an axial extent of the receptacle compartment. The axial extent of a receptacle, as measured along the coupling axis of the receptacle between the axial ends of the inner peripheral wall which defines the receptacle compartment, defines the height of the receptacle. The inner peripheral wall of the receptacle defines the shape, configuration, dimensions of the receptacle compartment. The receptacle may be in the form of a receptacle portion, a receptacle body, or a receptacle member. In some embodiments, a female connector comprises a peripheral wall which defines the receptacle. The peripheral wall may comprise an inner peripheral wall which defines the receptacle compartment and the receptacle compartment radial profile and an outer peripheral wall which surrounds the inner peripheral wall and defines the outer periphery of the receptacle. The peripheral wall may be a continuous wall or a non- continuous wall. In some embodiments, the outer peripheral wall of the receptacle depends from the panel portion and has a substantial portion of its axial extent which is spaced apart from or independent of the panel portion. For example, the outer peripheral wall may have, in percentage terms of its axial extent or of the maximum radial extent of the receptacle compartment, 55, 60, 65, 70, 75, 80, 90, 95, 100, or a range or any ranges defined by a combination of any of the aforesaid values and/or ranges which is laterally separated from the panel portion so that there is radial spatial separation between the outer peripheral wall and the panel portion from which the receptacle depends. In some embodiments, a minor portion of the axial extent of the receptacle is spaced apart from or independent of the panel portion, and the minor portion, in percentage terms of its axial extent or of the maximum radial extent of the receptacle compartment, is 5, 6, 7, 8, 9, 9, 10, or a range or any ranges defined by a combination of any of the aforesaid values and/or ranges.

[0081 ] A female snap connector comprises a snap-fit receptacle which is shaped and dimensioned for closely fitted engagement of a male snap engagement portion. When a female snap connector and a male snap connector are in closely-fitted snap engagement, the male engagement portion is subject to a small radially inward compression force exerted radially inwardly by the receptacle functioning as a female engagement portion, and the receptacle is subject to a small radial outward expansion force which is exerted radially outwardly by the male engagement portion.

[0082] The receptacle compartment of a female connector has a radial profile which is defined by the inner peripheral wall of the receptacle. The radial profile of the receptacle compartment of a female snap connector is characterized by a non-uniform radial extent in the axial direction, and typically includes a bulged radial profile of a bulged receptacle portion and a reduced radial profile of a reduced receptacle portion in the axial direction. The terms receptacle, coupling receptacle, snap-fit receptacle, receptacle portion, receptacle body, and receptacle member are interchangeably used herein unless the context requires otherwise.

[0083] The entry aperture is on or at one axial end of the receptacle and is an annular aperture which provides access for a male engagement portion so that a male engagement portion can enter into the receptacle compartment through that axial end and through the entry aperture and then enter into closely-fitted engagement with the receptacle. A receptacle may have an entry aperture on each of the two axial ends of the receptacle to facilitate entry or exit of a protrusion portion of a male connector from a selected one of the two axial ends.

[0084] The entry aperture has or may have a radial clearance which is smaller or slightly smaller than the maximum radial extent of a male engagement portion, and the maximum radial extent of a male engagement portion is typically located on the bulged portion of the male connector protrusion. A smaller radial clearance at the entry aperture than the maximum radial extent of the bulged portion usually means a radial constriction at the axial end of the receptacle. The bulged portion of a male connection means would need to overcome the radial constriction in order to enter the receptacle compartment from outside the receptacle compartment or to leave the receptacle if already inside the receptacle compartment. A minimum radial clearance extent of the receptacle is defined at the entry aperture.

[0085] A receptacle may comprise a first receptacle portion having a first receptacle compartment and a second receptacle portion having a second receptacle compartment. The first receptacle portion and the second receptacle portion are in series and are aligned on the coupling axis. The first receptacle portion has an axial end comprising the receptacle entry and the second receptacle portion extends axially away from the first receptacle portion and the receptacle entry. The first receptacle portion is to surround and snap on the neck portion of a corresponding male engagement portion upon snap engagement therewith and is referred to as a neck receptacle portion. The neck receptacle portion is also referred to as a neck portion engagement portion and comprises a neck receptacle compartment. The second receptacle portion is to surround and snap on the head portion of a corresponding male engagement portion upon snap engagement therewith and is referred to as a head receptacle portion. The head receptacle portion is also referred to as a head portion engagement portion and comprises a head receptacle compartment. The two receptacle portions, namely, the head receptacle portion and the neck receptacle portion, may be separate or integrally formed.

[0086] The engagement portion of a receptacle portion is an annular receptacle portion defined by a portion of the inner peripheral wall of the receptacle defining the receptacle portion. The engagement portion may be in the embodiments of an annular bracket portion, an annular bracket member, an annular collar portion, or an annular collar member. In some embodiments, a receptacle portion has an access aperture at each of its axial ends to facilitate entry and/or exit of a matched male engagement portion at either axial end.

[0087] In some embodiments, the receptacle may have only one receptacle portion, for example, only the head receptacle portion or only the neck receptacle portion.

[0088] The head receptacle portion comprises a head receptacle compartment which is adapted for making snap engagement with the head portion of a corresponding male connector, and has a radial clamping profile which is complementarily shaped and sized to match the radial profile of the bulged portion of the corresponding male connector.

[0089] The head receptacle portion is an enlarged receptacle portion, also referred to as a widened receptacle portion, or an enlarged portion in short. The head receptacle portion has a head receptacle portion radial profile which is an enlarged radial profile compared to the neck receptacle portion radial profile. The head receptacle portion radial profile extends in a peripheral direction to define an annular inner periphery of the head receptacle portion. The head receptacle portion radial profile and the inner periphery of the head receptacle portion is defined by a portion of the inner peripheral wall of the receptacle defining the head receptacle portion. The engagement portion of a head receptacle portion is typically in the form of an annular clamp or clip, and in example embodiments in the form of an annular bracket portion, an annular bracket member, an annular collar portion, or an annular collar member. The maximum radial clearance extent of the receptacle is usually defined in the head receptacle portion.

[0090] The portion of the inner peripheral wall of the receptacle defining the head receptacle portion and the head receptacle compartment has a radial profile of an indentation or a recess, with the indentation or access inwardly facing the coupling axis. The indentation has a radial profile which defines the head receptacle portion radial profile. The radial profile may be angled or curved and extends peripherally in a peripheral direction, that is annularly, to define the head receptacle compartment and its boundary. The peripheral direction is orthogonal to the coupling axis and is a tangential direction to a circle defining the annular clamp or clip. The annular clamp or clip is in the form of an annular channel which surrounds a core portion of the head receptacle portion. The head receptacle portion defines a female snap engagement portion of the female connection portion, and is referred to as a first engagement portion or a first snap engagement portion of the receptacle, or of the female connection portion, for ease of reference. The terms "channel" and "groove" are used interchangeably herein.

[0091 ] The head receptacle compartment has a maximum radial extent defining a maximum radial clearance and a maximum radial plane at an axial level referred to a maximum radial extent level. The maximum radial plane is also a maximum transversal plane. The radial extent of the head receptacle portion decreases as the axial distance from the maximum radial extent level increases. Specifically, the radial extent of the head receptacle portion decreases as the head receptacle portion extends away from the maximum radial extent level and towards the receptacle entry, and the radial extent of the head receptacle portion decreases as the head receptacle portion extends away from the maximum radial extent level and away from the receptacle entry. Therefore, the head receptacle portion tapers to narrow as its axial distance away from the maximum radial extent plane or the maximum radial extent level increases. Conversely, the head receptacle portion flares to widen as it extends axially towards the maximum radial extent plane or the maximum radial extent level.

[0092] The axial end of the head receptacle portion distal to the receptacle entry may be flat or curved, for example, may have the shape of a spherical cap or other desired shapes.

[0093] The neck receptacle portion comprises a neck receptacle compartment which is adapted for making snap engagement with the neck portion of a corresponding male connector and has a radial clamping profile which is complementarily shaped to match the radial profile of the neck portion of the corresponding male connector.

[0094] The neck receptacle portion is a reduced receptacle portion compared to the head receptacle portion radial profile. The neck receptacle portion is a reduced receptacle portion, since it has a neck receptacle portion radial profile which is smaller than the radial profile of the head receptacle portion radial profile. The reduced receptacle portion is also referred to as a narrowed receptacle portion, or a reduced portion in short. The neck receptacle portion radial profile is defined by a portion of the inner peripheral wall of the receptacle which defines the neck receptacle portion and the inner periphery of the neck receptacle portion. The neck receptacle portion radial profile extends in a peripheral direction to define an annular inner periphery of the neck receptacle portion. The portion of the inner peripheral wall of the receptacle which defines the neck receptacle portion and the neck receptacle compartment has a radial profile of an indentation or a recess, and the indentation or access is inwardly facing the coupling axis and the centre of the maximum radial plane of the head receptacle portion. The indentation has a radial profile which is or which defines the neck receptacle portion radial profile. The radial profile may be angled or curved and extends peripherally in a peripheral direction, that is annularly, to define a neck receptacle compartment and its boundary.

[0095] The engagement portion of an example neck receptacle portion is in the form of an annular clamp or an annular clip which surrounds and defines the neck receptacle portion. The annular clamp or clip may have a radial profile of a clamping bracket or a clamping collar. The neck receptacle portion in exemplary embodiments is in the form of an annular bracket portion, an annular bracket member, an annular collar portion, or an annular collar member. The terms "bracket" and "collar" are interchangeably used herein and shall bear the same meaning unless the context requires otherwise. A clamping bracket herein is an inclined bracket having a recess or indentation facing the coupling axis and the centre of the maximum radial plane of the head receptacle portion. The bracket extends peripherally in a peripheral direction to define a neck receptacle compartment portion and its boundary. The peripheral direction is orthogonal to the coupling axis and is a tangential direction to a circle defining the annular clamp or clip. The neck receptacle portion defines a female snap engagement portion of the female connection portion, and is referred to as a second engagement portion or a second snap engagement portion of the receptacle, or of the female connection portion, for ease of reference. This second engagement means, similar to the first engagement means, is a retention portion defining a female retention means. The minimum radial clearance extent of the receptacle is usually defined in the neck receptacle portion.

[0096] The reduced receptacle portion has a local maximum radial extent defining a local maximum radial plane at an axial level referred to a local maximum radial extent level. The local maximum radial plane is also a local maximum transversal plane. The radial extent of the neck receptacle compartment decreases as the axial distance away from the local maximum radial extent level towards the receptacle entry increases. Specifically, the radial extent of the neck receptacle compartment decreases as the neck receptacle compartment extends away from the local maximum radial extent level and towards and joins the receptacle entry. The neck receptacle compartment is a tapered receptacle portion which tapers to narrow as it extends axially towards the receptacle entry. Conversely, the neck receptacle compartment flares to widen as it projects axially away from the receptacle entry.

[0097] The tapered entry end of the neck receptacle portion is optionally shaped and sized to operate as an engagement portion, or more specifically a male engagement portion, for engaging with or snap on the narrowed neck portion of the corresponding male connection portion, for example, by wedged engagement. Therefore, this tapered entry end be regarded as a third snap engagement portion of the receptacle.

[0098] The tapering may follow a curve, for example, a concave curve, a straight slope or other desired profiles without loss of generality.

[0099] The receptacle of a female connection portion is adapted to accommodate the protrusion of a male connection portion such that when two building blocks having matched connection means are stacked and their matched corresponding connection means in releasable engagement, the corresponding connection surfaces of the building blocks are in flush abutment and even contact. To meet the accommodation requirements, the axial end or ceiling of the receptacle compartment which is distal to the entry end would need to be at an axial level sufficient to accommodate the protrusion.

[0100] Where the entry end of the receptacle is at the axial level of the connection surface, as is usually the case, the ceiling end of the receptacle would be at an axial level corresponding to the axial extent of the protrusion from the connection surface, unless the ceiling end is an open end that allows the protrusion to pass through. In general, the axial extent of the receptacle compartment is a fraction of the maximum radial extent, E, of the protrusion or of the receptacle, and the fraction is optionally between 15% and 80%, for example, in percentage terms, at 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, or a range or any ranges defined by a combination of any of the aforesaid values and/or ranges. Typically, the axial extent will be in the higher range of between 50% and 80% where the protrusion has a rounded end or partial spherical end and in the lower range of 15% and 60% where the protrusion has a flat head or flat axial end.

[0101 ] A head receptacle portion which is adapted to snap on the bulged portion has a radial clamping profile which is complementarily shaped to match the radial profile of the bulged of the head portion.

[0102] In order to provide sufficiently effective snap griping on the bulged portion, the axial extent of the radial clamping profile of the head receptacle portion, which is determined by the radial profile of the annular bracket, would be comparable to the axial extent of the bulged portion of the corresponding male engagement portion. In general, the axial extent of the head receptacle portion would be a fraction of the maximum radial extent of the bulged portion, and the fraction would optionally be between 10% and 40%, for example, in percentage terms, at 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, or a range or any ranges formed by a combination of any of the aforesaid values as limits of a range or limits of ranges. [0103] The head receptacle portion is optionally symmetrical about a radial plane of symmetry, which corresponds to the maximum radial extent plane of the bulged receptacle portion or the bulged portion of the protrusion on snap engagement. The plane of symmetry divides the head receptacle portion into symmetrical halves about the radial plane of symmetry. The head receptacle portion tapers to narrow as it extends axially away from the maximum radial extent plane to taper. The head receptacle portion optionally follows a concave profile or has a concave radial profile as it extends axially to taper. Optionally, the concave profile follows or matches the convex profile of the corresponding bulged portion. In some embodiments, the concave profile follows a concave curvature having a diameter equal to or comparable to the maximum radial extent of the bulged portion. The tapering may follow a straight slope or other desired profiles without loss of generality. The concave curve may have a radius of curvature comparable to half the maximum radial extent E.

[0104] The radial extent of the head receptacle portion at an axial end of the head receptacle portion where symmetry about the plane of symmetry ends is a fraction of the maximum radial extent of the bulged receptacle portion, and the fraction would optionally be between 95% and 99%, for example, in percentage terms, at 95, 96, 97, 98, 99, or a range or any ranges formed by a combination of any of the aforesaid values as limits of a range or limits of ranges.

[0105] The neck receptacle portion has an axial extent to provide snap grip on the neck portion of the male connector. The axial extent is a fraction of the maximum radial extent of the bulged portion which, in percentage terms, is optionally between 2 and 10, for example, at 2, 3, 4, 5, 6, 7, 8, 9, 10, or a range or any ranges defined by a combination of any of the aforesaid values and/or ranges.

[0106] In order to provide sufficient or effective snap clamping on the neck portion of the protrusion, the axial extent of the radial clamping profile of the neck receptacle portion, which is the radial profile of the annular bracket, would be comparable to the axial extent of the neck portion of the corresponding male engagement portion. In general, the axial extent of the neck receptacle portion would be a fraction of the radial extent of the neck portion at the base surface, and the fraction would optionally be between 10% and 35%, for example, in percentage terms, at 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 35, or a range or any ranges formed by a combination of any of the aforesaid values as limits of a range or limits of ranges.

[0107] The axial extent of the neck receptacle portion can be expressed as a fraction of the maximum radial extent of the receptacle, and the fraction would optionally be between 1 .9% and 5%, for example, in percentage terms, at 1 .9, 2, 2.0, 2.5, 3, 3.5, 4, 4.0, 4.5, 5, or a range or any ranges formed by a combination of any of the aforesaid values as limits of a range or limits of ranges.

[0108] The neck receptacle portion tapers to narrow as it extends axially towards the access aperture to define a narrowed access aperture to facilitate snap fit.

[0109] As a result of the tapering, the access aperture at the tapered axial end of the neck receptacle portion has a radial extent which is a fraction of the maximum radial extent of clearance of the internal compartment of the receptacle, and the fraction is optionally between 85% and 96%, for example, in percentage terms, at 85, 90, 95, 96, or a range or any ranges formed by a combination of any of the aforesaid values as limits of a range or limits of ranges.

[01 10] As a result of the tapering, the inner peripheral wall of the neck receptacle portion is at an inclination angle to a radial plane at the access aperture axial end of the neck receptacle portion. The inclination angle is optionally between 50 degrees and 88 degrees, for example, in degree terms, 50, 55, 60, 65, 70, 75, 70, 80, 85, 88, or any range or ranges defined by a combination of any of the aforesaid values and/or ranges. Preferably, the inclination angle corresponds to the joining angle to facilitate closely fitted engagement between the neck receptacle portion and the neck portion.

[01 1 1 ] Where the receptacle comprises both the neck receptacle portion and the head receptacle portion, both the neck receptacle portion and the head receptacle portion may be defined by an integrally formed peripheral wall of the receptacle, and the axial extent of the peripheral wall of the receptacle would optionally be between 30% and 85% of R, for example, in percentage terms, at 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, or a range or any ranges defined by a combination of any of the aforesaid values and/or ranges.

Figures

[01 12] The present disclosure is described by way of example with reference to the accompany drawings, in which:

Figure 1 A1 is a perspective view of an example building block 100 according to the disclosure,

Figure 1 A2 is a plan view of the example building block 100 of Figure 1 A1 ,

Figure 1 A3 is a longitudinal cross-sectional view of the example building block 100 of Figure 1 A1 taken along line A-A' of Figure 1 A2,

Figure 1 A4 is an elevation view of the example building block 100 of Figure 1 A1 , Figure 1 B1 is a perspective view of the example building block 100B,

Figure 1 B2 is a plan view of the example building block 100B,

Figure 1 B3 is a longitudinal cross-sectional view of the example building block 100B taken along a section line AB-AB' shown on Figure 1 B2,

Figure 1 B4 is an elevation view of the example building block 100B,

Figure 1 C1 is a perspective view of the example building block 100C,

Figure 1 C2 is a plan view of the example building block 100C,

Figure 1 C3 is a longitudinal cross-sectional view of the example building block 100C taken along the section line AC-AC shown on Figure 1 C2,

Figure 1 C4 is an elevation view of the example building block 100C,

Figure 1 D1 is a perspective view of the example building block 100D,

Figure 1 D2 is a plan view of the example building block 100D,

Figure 1 D3 is a longitudinal cross-sectional view of the example building block 100D taken along the section line AD-AD' shown on Figure 1 D2,

Figure 1 D4 is an elevation view of the example building block 100D,

Figure 1 E1 is a perspective view of the example building block 100E,

Figure 1 E2 is a plan view of the example building block 100E,

Figure 1 E3 is a longitudinal cross-sectional view of the example building block 100E taken along the section line AE-AE' shown on Figure 1 E2,

Figure 1 E4 is an elevation view of the example building block 100E,

Figure 2A1 is a perspective view of an example building block 200 according to the disclosure, Figure 2A2 is a plan view of the example building block 200,

Figure 2A3 is a longitudinal cross-sectional view of the example building block 200 taken along line B-B' of Figure 2A2,

Figure 2A4 is an elevation view of the example building block 200,

Figure 2B1 is a perspective view of the example building block 200B,

Figure 2B2 is a plan view of the example building block 200B, Figure 2B3 is a longitudinal cross-sectional view of the example building block 200B taken along a section line BB-BB' shown on Figure 2B2,

Figure 2B4 is an elevation view of the example building block 200B,

Figure 2BA1 is a perspective view of an example building block 200BA,

Figure 2BA2 is a plan view of the example building block 200BA,

Figure 2BA3 is an elevation view of the example building block 200BA showing a section line BBA- BBA',

Figure 2BA4 is a traverse cross-section view of the example building block 200BA taken along line BBA-BBA' of Figure 2BA3,

Figure 2C1 is a perspective view of the example building block 200C,

Figure 2C2 is a plan view of the example building block 200C,

Figure 2C3 is a longitudinal cross-sectional view of the example building block 200C taken along line NC-NC of Figure 2C2,

Figure 2C4 is an elevation view of the example building block 200C,

Figure 3A1 is a perspective view of the example building block 300,

Figure 3A2 is a plan view of the example building block 300,

Figure 3A3 is a longitudinal cross-sectional view of the example building block 300 taken along line C-C of Figure 3A2,

Figure 3B1 is a perspective view of the example building block 300B,

Figure 3B2 is a plan view of the example building block 300B,

Figure 3B3 is a longitudinal cross-sectional view of the example building block 300B taken along line CB-CB' of Figure 3B2,

Figure 3C1 is a perspective view of the example building block 300C,

Figure 3C2 is a plan view of the example building block 300C,

Figure 3C3 is a longitudinal cross-sectional view of the example building block 300C taken along line CC-CC of Figure 3C2,

Figure 4A1 is a perspective view of the example building block sub-assembly 400,

Figure 4A2 is a plan view of the example building block sub-assembly 400, Figure 4A3 is a longitudinal cross-sectional view of the example building block 400 taken along a section line of Figure 4A2,

Figure 4B1 is a perspective view of the example building block sub-assembly 400B,

Figure 4B2 is a plan view of the example building block sub-assembly 400B,

Figure 4B3 is a longitudinal cross-sectional view of the building block sub-assembly 400B taken along a section line of Figure 4B2,

Figure 5A1 is a perspective view of the example building block sub-assembly 500,

Figure 5A2 is a plan view of the example building block sub-assembly 500,

Figure 5A3 is a longitudinal cross-sectional view of the building block sub-assembly 500 taken along a section line AD-AD in Figure 5A2,

Figure 5B1 is a perspective view of the example building block sub-assembly 500B,

Figure 5B2 is a plan view of the example building block sub-assembly 500B,

Figure 5B3 is a longitudinal cross-sectional view of the building block sub-assembly 500B taken along a section line AE-AE in Figure 5B2,

Figure 5C1 is a perspective view of the example building block sub-assembly 500C,

Figure 5C2 is a plan view of the example building block sub-assembly 500C.

Figure 5D1 is a perspective view of the example building block sub-assembly 500D,

Figure 5D2 is a plan view of the example building block sub-assembly 500D.

Figure 5E1 is a perspective view of the example building block sub-assembly 500E,

Figure 5E2 is an elevation view of the example building block sub-assembly 500E.

Figure 5E3 is a plan view of the building block sub-assembly 500E, and

Figure 5E4 is an enlarged view of the circled portion of Figure 5E3.

Description

[01 13] An example building block 100 comprises an example plurality of connection portions, as depicted in Figures 1 A1 , 1 A2, 1 A3 and 1 A4. The example plurality of connection portions forms an ensemble of connection portions comprising a first connection portion 142, a second connection portion 144 and a third connection portion 146 which are connected in series. In the example, the second connection portion 144 is in abutment with both the first connection portion 142 and the third connection portion 146.

[01 14] The connection portion is delimited by a first plane and a second plane which is parallel to the first plane and has a center axis X-X'. The first plane is orthogonal to the center axis and at a first axial level. The second plane is at a second axial level which is spaced apart from the first axial level in an axial direction, the axial direction being in the direction of the center axis. The axial thickness of the connection portion is defined by the axial distance between the first plane and the second plane.

[01 15] The connection portion 142, 144, 146 has a characteristic center axis and comprises a core portion 120 and an engagement portion. The example engagement portion is formed on the outer periphery of the core portion and extends along a circular path to form a distributed engagement means in an example form of a ring-shaped engagement device. The distributed engagement means has a distributed engagement surface to facilitate distributed engagement. The circular path is orthogonal to the center axis X-X' and the engagement portion is orthogonal to the center axis and defines an engagement plane which is orthogonal to the center axis.

[01 16] The example core portion is hollow and has an internal bore which is defined by a bore surface which is a bore defining surface. The internal bore has a bore axis and the bore surface is a cylindrical surface. The example internal bore is a through bore that extends through the connection portion and extends axially between the first plane and the second plane. The cylindrical surface of the internal bore has a cylindrical axis which is aligned with the center axis X-X' of the connection portion. In some embodiments, the connection portion is not hollow or does not have a through bore or an internal bore at all. In some embodiments, the internal bore has a non-circular cross-section, and may have a cross section of a square or a regular polygonal. In some embodiments, the bore axis and the center axis of the connection portion are not aligned. For example, the bore axis and the center axis may be parallel and offset from each other or at an angle to each other.

[01 17] The engagement portion has a center axis which is coaxial with the center axis X-X' of the connection portion and which defines a coupling axis and coupling direction. The example engagement portion comprises mechanical snap-fit mating features to facilitate making of snap- fit engagement with a matched counterpart engagement portion of a matched connector of a counterpart building block along the coupling direction. The mechanical snap-fit mating features define an engagement surface in the form of a snap-fit mating surface. The example engagement portion comprises a peripheral protrusion which extends around the outer periphery of the core portion and projects away from the outer periphery of the core portion in a radial direction, the radial direction is defined with respect to the center axis. The exposed or outward facing surface of the peripheral protrusion defines the snap-fit mating surface or the engagement surface in this example, and the peripheral protrusion defines an engagement plane which is orthogonal to the center axis.

[01 18] The radial projection of the engagement portion at an axial level defines a radial extent of the engagement portion at that axial level. The radial extent also defines a lateral extent of the engagement portion, The lateral extent of the engagement portion varies as it extends in the coupling direction to facilitate snap fitting.

[01 19] The peripheral protrusion extends in an axial direction between the first plane and the second plane to define an axial extent, or thickness of the engagement portion, the axial direction being in the direction of the center axis.

[0120] The radial extent of the engagement portion varies as the engagement portion extends in the axial direction from the first plane to the second plane or vice versa.

[0121 ] A connection portion having the peripheral protrusion is generally regarded as a male-type connector or a male-type fastener, since the peripheral protrusion is to function generally as a male-type mechanical mating feature.

[0122] Referring to Figures 1 A3 and 1 A4, the radial extent of the example engagement portion 142', 144' and 146' of the connection portions 142, 144, 146 gradually increases as the axial distance away from the first plane increases. The radial extent reaches a maximum at a radial plane M-M' which is approximately half-way between the first plane and the second plane. The radial extent of the example engagement portion 144' of the connection portion 144 decreases gradually as the axial distance away from the first plane and the plane M-M' increases. In this example, the first plane is a plane shared by the engagement portions 142' and 144' and the second plane is a plane shared by the engagement portions 144' and 146'. The engagement portion 144' is substantially symmetrical about the plane M-M' which is a mid-plane and the radial extent at the two axial ends is the same and a minimum, while each of the end engagement portions 142' and 146' is non-substantially symmetrical about the maximum plane M-M'.

[0123] The example engagement portion is a ripple-shaped portion having a rippled-shaped surface in the coupling direction, and the ripple-shaped surface has a ripple-shaped profile, as depicted in Figures 1 A3 and 1 A4. The ripple-shaped surface is offset from the coupling axis and defines the snap-fit mating surface of the engagement portion. [0124] The example ripple-shaped surface is an outward facing surface which is convexly curved. The ripple-shaped surface defines an outer peripheral surface of the connection portion and is circularly symmetrical about the center axis X-X'. The outer peripheral surface is formed by revolving the convexly curved outward facing surface by 360 degrees about the center axis X-X' in a circular path.

[0125] The ensemble of connection portions comprises a stack of three example connection portions 142, 144 and 146 which are center axis aligned. The stack comprises, in the axial direction parallel to the center axis X-X', a first engagement portion 142', a second engagement portion 144', and a third engagement portion 146'. The second engagement portion 144' is intermediate the first and third connection portions and is in abutment with the first and third connection portions. The center axes of the serially connected connection portions are joined to form a distribution axis. The distribution axis is co-axial with the center axes in this example. In some embodiments, the distribution axis may be curved, with some or all of the center axes of the serially connected connection portion aligned along a curve.

[0126] The engagement portions of the example building block 100 are connected in series so that the first plane of one engagement portion is in abutment with either the first plane or the second plane of another engagement portion.

[0127] With the radial extent of the engagement portion gradually decreases with a decreasing axial distance from an axial end of the engagement portion, the engagement portion has a tapered axial end. When two engagement portions having the same or similar tapering characteristics are in abutment, the tapered axial ends of the engagement portions which are in abutment cooperate or intersect to form an indentation having a tapered profile. The indentation extends around the periphery of the building block and forms a ring of tapered indentation, and the indentation tapers to narrow towards the center axis or towards the distribution axis.

[0128] The tapered axial ends of the adjacent engaging portions in abutment merge at a merging angle to define a tapered indentation and the merged tapered ends has an outline of a ripple and forms a ripple portion or a rippled shaped portion on the peripheral surface of the building block 100. The tapered axial ends of the adjacent engaging portions in abutment merge or intersect at a merging plane and at merging angle, the merging plane being parallel to the engagement plane. The merging angle may be an acute angle, a right angle or an obtuse angle. In some embodiments, the merging angle is between 30 degrees and 60 degrees or between 120 degrees and 150 degrees. [0129] In this example, the lateral extent of the axial end (non-abutting end) of the first engagement portion 142' and the third engagement portions 146' which is not in abutment with the second engagement portion is slightly larger than that at the abutting axial end. Therefore, the non-abutting end is slightly larger than the abutting end. In some embodiments, the non-abutting end is smaller than the abutting end to facilitate easier entry and exit from the stack.

[0130] In some embodiments such as the present, the merging angles are identical or approximately identical.

[0131 ] The tapering axial end of an engagement portion inclines at a tapering angle to the merging plane to merge with an adjacent engagement portion in abutment. In some embodiments such as the present, the tapering angles are the same or substantially identical, although the tapering angles may be different when non-symmetry is required or desired.

[0132] In some embodiments such as the present, the axial end of an engagement portion follows a convex curvature on approaching the merging plane. In some embodiments, for example when the engagement portions are formed on an internal bore, the axial end of an engagement portion follows a concave curvature on approaching the merging plane.

[0133] In some embodiments such as the present, the ripple-shaped profiles of adjacent engagement portions are in abutment and intersect. In other embodiments, adjacent ripple- shaped profiles may be spaced apart, axially or radially, and do not intersect.

[0134] In some embodiments such as the present, the component connection portions forming the stacked ensemble are of substantially identical latent extents, in some embodiments, the component connection portions have different lateral extents to suit specific applications. Connection portions have substantially identical latent extents when the lateral extents of their lateral plane of maximum lateral extent, that is M-M', are substantially identical.

[0135] In some embodiments, the engagement portion and the core portion are integrally formed as a single piece.

[0136] An example building block 200B comprises an example plurality of connection portions, as depicted in Figures 2B1 , 2B2, 2B3 and 2B4. The example plurality of connection portions forms an ensemble of connection portions comprising a first connection portion 242B, a second connection portion 244B, a third connection portion 246B and a fourth connection portion 248B. The example plurality of four connection portions are connected in series to form a stack of connection portions. In the example, the second connection portion 244B is in abutment with the first connection portion 242B and the third connection portion 246B, and the third connection portion 246B is in abutment with the second connection portion 244B and the fourth connection portion 248B.

[0137] Each connection portion is delimited by a first plane and a second plane which is parallel to the first plane and has a center axis YB-YB'. The first plane is orthogonal to the center axis and at a first axial level. The second plane is at a second axial level which is spaced apart from the first axial level in an axial direction, the axial direction being in the direction of the center axis. The axial thickness of the connection portion is defined by the axial distance between the first plane and the second plane.

[0138] The connection portion 242B, 244B, 246B, 248B has a characteristic center axis and comprises a core portion 220B and an engagement portion. The example engagement portion is formed inside the core portion and extends along a circular path to form a distributed engagement means in an example form of a ring-shaped engagement device. The distributed engagement means has a distributed engagement surface to facilitate distributed engagement. The circular path is orthogonal to the center axis and the engagement portion is orthogonal to the center axis and defines an engagement plane which is orthogonal to the center axis.

[0139] The example core portion is hollow and has an internal bore which is delimited by a bore surface, which is an interior peripheral surface of the internal bore. The internal bore has a bore axis and the characteristics of the bore surface are determined by the mechanical snap-fit mating features of the engagement portion. The internal bore has a bare bore surface on which the mechanical snap-fit mating features are formed. The physical differences between the bare bore surface and the interior peripheral surface of the internal bore are the formation of mechanical snap-fit mating features and lack thereof. The bare bore surface is a generally cylindrical surface. The example internal bore is a through bore that extends through the connection portion and extends axially between the first plane and the second plane. The bore axis is aligned with the center axis of the connection portion. In some embodiments, the bare internal bore has a non- circular cross-section, and may have a cross section of a square or a regular polygonal.

[0140] The engagement portion has a center axis which is coaxial with the center axis YB-YB' of the connection portion and which defines a coupling axis and coupling direction. The example engagement portion comprises mechanical snap-fit mating features to facilitate making of snap- fit engagement with a matched counterpart engagement portion of a matched connector of a counterpart building block along the coupling direction. The mechanical snap-fit mating features define an engagement surface in the form of a snap-fit mating surface. The example engagement portion comprises a peripheral indentation which extends around the interior periphery of the core portion and projects towards the outer periphery of the core portion in a radial direction, the radial direction being defined with respect to the center axis. The exposed or inner facing surface of the peripheral indentation defines the snap-fit mating surface in this example, and the peripheral indentation defines an engagement plane which is orthogonal to the center axis.

[0141 ] A connection portion having the peripheral indentation is generally regarded as a female- type connector or a female-type fastener, since the peripheral indentation is to function generally as a female-type mechanical mating feature, for example, for making snap-fit engagement with the peripheral protrusion of the connection portions of the building block 100.

[0142] The radial extent of an aperture of the engagement portion at an axial level defines a radial extent of the engagement portion at that axial level. The radial extent also defines a lateral extent of the engagement portion. The lateral extent of the engagement portion varies as it extends in the coupling direction to facilitate snap fitting or snap-fit engagement with a matched counterpart engagement portion.

[0143] The peripheral indentation extends in an axial direction between the first plane and the second plane to define an axial extent, or thickness of the engagement portion, the axial direction being in the direction of the center axis.

[0144] The radial extent of the engagement portion varies as the engagement portion extends in the axial direction from the first plane to the second plane or vice versa.

[0145] Referring to Figure 2B3, the radial extent of the example engagement portion of the connection portions 242B, 244B, 246B, 248B gradually increases as the axial distance away from the first plane increases. The radial extent reaches a maximum at a radial plane which is a maximum plane approximately half-way between the first plane and the second plane. The radial extent of the example engagement portion of the connection portion 242B, 244B, 246B, 248B decreases gradually as the axial distance away from the first plane and the radial plane increases. As an example, the first plane is a plane shared by the engagement portions 242B' and 244B' and the second plane is a plane shared by the engagement portions 244B' and 246B'. The engagement portion 244B' is substantially symmetrical about the radial plane - which is a mid- plane and the radial extent at the two axial ends is the same and a minimum. In some embodiments, the engagement portion is non-symmetrical about the maximum radial plane.

[0146] The example engagement portion is a ripple-shaped portion having a rippled-shaped surface in the coupling direction, and the ripple-shaped surface has a ripple-shaped profile, as depicted in Figure 2B3. The ripple-shaped surface is offset from the coupling axis and defines the snap-fit mating surface of the engagement portion.

[0147] The example ripple-shaped surface is an inward facing surface which is concavely curved. The ripple-shaped surface defines an inner peripheral surface of the connection portion and is circularly symmetrical about the center axis YB-YB'. The inner peripheral surface is formed by revolving the concavely curved inward facing surface by 360 degrees about the center axis YB- YB' in a circular path.

[0148] The ensemble of connection portions comprises a stack of four example connection portions which are center axis aligned. The stack comprises, in the axial direction parallel to the center axis, a first engagement portion 242B', a second engagement portion 244B', a third engagement portion 246' and a fourth engagement portion 248B'. The second engagement portion 244B' is intermediate the first and third connection portions and is in abutment with the first and third connection portions. The center axes of the serially connected connection portions are joined to form a distribution axis. The distribution axis is co-axial with the center axes in this example. In some embodiments, the distribution axis may be curved, with some or all of the center axes of the serially connected connection portion aligned along a curve.

[0149] The engagement portions of the example building block 200B are connected in series so that the first plane of one engagement portion is in abutment with either the first plane or the second plane of another engagement portion.

[0150] With the radial extent of the engagement portion gradually decreases with a decreasing axial distance from an axial end of the engagement portion, the engagement portion has a tapered axial end. When two engagement portions having the same or similar tapering characteristics are in abutment, the tapered axial ends of the engagement portions which are in abutment cooperate or intersect to form a protrusion having a tapered profile. The protrusion extends around the inner periphery of the internal bore and forms a ring of tapered protrusion projecting radially inwards from the bare bore surface, and the protrusion tapers to narrow towards the center axis or towards the distribution axis. In this example, the tapered protrusion resembles the shape of a saw tooth.

[0151 ] The tapered axial ends of the adjacent engaging portions in abutment merge at a merging angle to define a tapered indentation and the merged tapered ends has an outline of a ripple and forms a ripple portion or a rippled shaped portion on the bare bore surface. The tapered axial ends of the adjacent engaging portions in abutment merge or intersect at a merging plane and at merging angle, the merging plane being parallel to the engagement plane. The merging angle may be an acute angle, a right angle or an obtuse angle. In some embodiments, the merging angle is between 30 degrees and 60 degrees or between 120 degrees and 150 degrees.

[0152] A connection portion of the building block may comprise an optional engagement portion on an exterior periphery. The optional engagement portion is an engagement portion of the type having the same features and characteristics as that of engagement portion of the building block 100 or 100B, which engagement portion is referred to as an external engagement portion herein for succinctness. In this example, the optional external engagement portion 242B", 244B", etc. is concentric with the engagement portion 242B', 244B', etc. of the building block 200B, which engagement portion is referred to as an internal engagement portion herein for succinctness. In this example, the optional external engagement portion is axially aligned with the engagement portion of the building block 200B so that the first and second planes are coterminous. In some embodiment, the internal and external engagement portion are non-coaxial and/or non-axially aligned.

[0153] An example building block 200BA comprises an example plurality of connection portions 242BA, 244BA, 246BA, 248BA, as depicted in Figures 2BA1 to 2BA4.

[0154] The four example connection portions are connected in series to form a building block 200BA having a curved and elongated main body. The example plurality of connection portions is aligned along a curved longitudinal distribution axis BBA-BBA'. Except for the aforesaid differences, the building block 200BA is identical to the building block 200B and the description in relation to the building block 200B is incorporated herein by reference and applied mutatis mutandis, with reference numerals appended with a suffice "A". Adjacent connection portions 242BA, 244BA, 246BA, 248BA of the building block 200BA are in abutment and a joining portion interconnecting adjacent connection portion has a fan shape or an arc shape to define curvature of the curved distribution axis BBA-BBA'. In some embodiments, some of the adjacent connection portions 242BA, 244BA, 246BA, 248BA may not be in abutment. In some embodiments, adjacent connection portions are separated by an axial distance comparable to or smaller than the axial extent of a connection portion.

[0155] An example building block 100B depicted in Figures 1 B1 to 1 B4 comprises a main body and an ensemble of four connection portions 142B, 144B, 146B, 148B formed on the main body. The ensemble of connection portions comprises an example plurality of four engagement portions 142B', 144B', 146B', 148B'. The axial lengths of all the four engagement portions are identical and each engagement portion is symmetrical about its maximum lateral dimension plane MB-MB'. Except for the aforesaid differences, the building block 100B is identical to the building block 100 and the description in relation to the building block 100 is incorporated herein by reference and applied mutatis mutandis, with numerals appended with a suffix "B". As depicted in Figures 1 B1 and 1 B3, the four engagement portions are connected in series, with adjacent engagement portions in abutment contact and the convexly curved portions of the curved ripple-shaped profiles in intersection.

[0156] An example building block 100C depicted in Figures 1 C1 , 1 C2, 1 C3 and 1 C4 comprises a main body and an ensemble of example connection portions on the main body. The ensemble comprises an example plurality of two connection portions 142C, 144C and the two connection portions are connected in series and in abutment contact. The main body is a hollow cylindrical body extending along a cylindrical axis XC-XC which is also a longitudinal axis and a center axis of the main body. The hollow cylindrical body defines a cylindrical bore which extends along the cylindrical axis XC-XC. Each of the two connection portions is a ring-shaped member having a center axis and is circularly symmetrical about the center axis, and the center axes of the connection portions 142C and 144C are axially aligned or coaxial.

[0157] In this example, the first connection portion comprises a first engagement portion 142C, the second connection portion comprises a second engagement portion 144C, and the first engagement portion 142C and the second engagement portion 144C having a same lateral extent. Each engagement portion is a protrusion formed on the cylindrical main body and projects radially away from the main body and from the center axis XC-XC. The example engagement portion is a ripple-shaped portion having a ripple-shaped profile extending along an axial direction, the axial direction being parallel to and offset from the center axis XC-XC. The ripple-shaped portions of the engagement portions or connection portions in abutment are in abutment and intersection. This example building block 100C may be considered as consisting of the first and the second connection portions, the second and the third connection portions, or the first and the third connection portions, of the example building block 100, and the descriptions in relation thereto, especially descriptions on the ripple-shaped portions and the inter-relationship between the abutting ripple-shaped portions are incorporated herein by reference where appropriate.

[0158] An example building block 100D depicted in Figure 1 D1 comprises a main body and an ensemble of example connection portions on the main body. The ensemble comprises an example plurality of four connection portions 142D, 144D, 146D, 148D and the four connection portions are connected in series and in abutment contact. The main body is a hollow cylindrical body extending along a cylindrical axis XD-XD' which is also a longitudinal axis and a center axis of the main body. The hollow cylindrical body defines a cylindrical bore which extends along the cylindrical axis XD- XD'. Each of the two connection portions is a ring-shaped member having a center axis and is circularly symmetrical about the center axis, and the center axes of the connection portions 142D, 144D, 146D, 148D are axially aligned or coaxial.

[0159] In this example, the first connection portion comprises a first engagement portion 142D', the second connection portion comprises a second engagement portion 144D', the third connection portion comprises a third engagement portion 146D' and the fourth connection portion comprises a fourth engagement portion 148D'. The four engagement portions are identical and have the same lateral and axial extent. Each engagement portion is a protrusion formed on the cylindrical main body and projects radially away from the main body and from the center axis XD- XD'. The example engagement portion is a ripple-shaped portion having a ripple-shaped profile extending along an axial direction, the axial direction being parallel to and offset from the center axis XD-XD'. The ripple-shaped portions of the engagement portions or connection portions in abutment are in abutment and intersection.

[0160] This example building block 100D may be considered as being formed by any of the connection portions 142D, 144D, 146D, 148D in repetition without loss of generality, and the descriptions in relation thereto, including descriptions on the ripple-shaped portions and the interrelationship between the abutting ripple-shaped portions are incorporated herein by reference where appropriate.

[0161 ] An example building block 100E depicted in Figures 1 E1 , 1 E2, 1 E3 and 1 E4 comprises a main body and an ensemble of example connection portions on the main body. The ensemble comprises an example plurality of two connection portions and the two connection portions are connected in series and in abutment contact. The main body is a hollow cylindrical body extending along a cylindrical axis XE-XE' which is also a longitudinal axis and a center axis of the main body. The hollow cylindrical body defines a cylindrical bore which extends along the cylindrical axis XE- XE'. Each of the two connection portions is a ring-shaped member having a center axis and is circularly symmetrical about the center axis, and the center axes of the connection portions 142E and 144E are axially aligned or coaxial.

[0162] In this example, the first connection portion comprises a first engagement portion 142E' and the second connection portion comprises a second engagement portion 144E'. The first engagement portion 142E' has a larger lateral extent and the second engagement portion 144E' has a smaller lateral extent.

[0163] Each engagement portion is a protrusion formed on the cylindrical main body and projects radially away from the main body and from the center axis XE-XE'. The example engagement portion is a ripple-shaped portion having a ripple-shaped profile extending along an axial direction, the axial direction being parallel to and offset from the center axis XE-XE'. The ripple-shaped portion has the same description as that of the building block 100 and the description is incorporated herein mutatis mutandis.

[0164] In this example, the ripple-shaped portions of the engagement portions or connection portions in abutment are not in abutment or intersection. The ripple-shaped portions are spaced apart in the radial direction but not in the axial direction, the radial and axial directions being with reference to the center axis XE-XE'.

[0165] The engagement portions or connection portions of the building block examples 100, 100B, 100C, 100D, 100E are male-type connectors including male-type engagement portions or male- type connection portions.

[0166] The male-type connector is for entry into snap fit engagement or wedged engagement with a matched corresponding female-type connector on moving relatively to the female connector in a coupling direction which is in the direction of the center axis of the building block. In example embodiments such as the present, the tapered indentation formed by intersection of abutting ripple-shaped profiles of adjacent engagement portions defines a perimetrically or peripherally extending tapered groove for making wedged engagement with a corresponding wedging portion of a counterpart female connector. The tapered groove tapers to narrow as the groove extends radially towards the main body or the center axis.

[0167] The peripheral protrusion of the male-type connector extends circumferentially about the center axis and defines an engagement plane which is orthogonal to the coupling direction.

[0168] In example embodiments such as the present, the connections portions and their coupling planes are parallel. In other embodiments, the connections portions and there coupling planes are non-parallel.

[0169] An example building block 200 comprises an example main body 220 and an ensemble of connection portions 240 formed on the example main body, as depicted in Figures 2A1 to 2A4. The example main body 220 has a generally cylindrical shape and a cylindrical axis Υ ', which is also a longitudinal axis and a center axis of the main body 220. The example main body is hollow and has an internal bore which extends axially along the cylindrical axis Υ '. The main body 220 and the internal bore is coaxial and share a common center axis Υ ', and the example main body is substantially circularly symmetrical about the cylindrical axis Υ '. The main body extends axially along the direction of the cylindrical axis Y-Y' and the ensemble of connection portions 240 comprises an example plurality of two connection portions 242, 244.

[0170] The two connection portions 242, 244 are distributed along the length of the main body and the adjacent connection portions are in abutment. Each connection portion 242, 244 is a ring- shaped member which extends in a direction orthogonal to the cylindrical axis Y-Y' and defines an engagement plane which is orthogonal to the cylindrical axis ΥΎ'. The two connection portions 242, 244 share a common center axis and are therefore are axially aligned or coaxial.

[0171 ] Each connection portion 242, 244 has an internal boundary wall defining an inner peripheral surface, the inner peripheral surface extending around the cylindrical axis Y-Y' as a center axis and defining an internal bore and an engagement portion 242', 244' of the connection portion. The internal boundary wall is shaped to define a peripheral indentation which retracts radially away from the center axis Y-Y' and into the main body 220 as the internal boundary wall extends in an axial direction parallel to the center axis Y-Y'. The inner peripheral surface faces the internal bore and the center axis Y-Y' and defines an inner boundary of the engagement portion. The inner boundary of the engagement portion is also the outer boundary of the internal bore and defines a clearance profile of the engagement portion or a clearance profile of the internal bore.

[0172] The inner peripheral surface extends around the inner periphery of the main body to define a distributed engagement means. The distributed engagement means is distributed around the inside of the main body and is adapted for making coupled engagement with a matched distributed engagement means of a counterpart connector having matching and compatible mating features.

[0173] The internal bore has an axial profile which defines an internal clearance profile of the building block. The internal bore has a transversal clearance profile and a transversal clearance dimension at an axial level. The transversal clearance profile and the transversal clearance dimension change as the internal bore extends in the axial direction, so that the internal bore has a non-uniform transversal clearance profile in the axial direction, as depicted in Figure 2A3.

[0174] In the example of Figure 2A1 , the example engagement portion has a ripple-shaped engagement portion 242', 244' which extends around the inner periphery of the main body and is surrounded by the main body. The ripple-shaped engagement portion 242', 244' has an inner surface having a ripple-shaped profile as it extends in the axial direction, the axial direction being parallel to the center axis Y-Y'. The ripple-shaped profile extends in the axial direction and is offset from the center axis Y-Y'. The inner surface having the ripple-shaped profile extends around the main body and about the center axis Y-Y' to define the inner peripheral surface of the engagement portion. [0175] The example ripple-shaped inner surface is concavely curved and the concavely curved inner surface is inward facing, that is, facing the internal bore and the center axis B-B'. The inward facing surface of the example engagement portion is the inner peripheral surface of the main body which extends around the internal body and is circularly symmetrical about the center axis Υ '. In a perspective, the inner peripheral surface of the main body can be considered as being formed by revolving the concavely curved inward facing surface for 360 degrees about the center axis Y- Y' following a circular path.

[0176] As the inner surface of the example engagement portion has a ripple-shaped profile in the axial direction, the transversal clearance dimension of the engagement portion changes as the engagement portion extends in the axial direction, the transversal clearance dimension being a transversal dimension measured in a direction orthogonal to the center axis Υ '. More specifically, the transversal clearance dimensions vary between a maximum clearance dimension providing a maximum transversal clearance and a minimum clearance dimension providing a minimum transversal clearance.

[0177] The ensemble of connection portions 240 comprises, in the axial direction, a first engagement portion 242' and a second engagement portion 244' which are in abutment.

[0178] The first engagement portion 242' is at a first axial free end of the building block 200 and extends between the first axial free end and a common boundary with the second engagement portion 244'. The first engagement portion 242' has a first transversal clearance dimension and defines first transversal clearance dimension plane at the first axial free end, the transversal clearance dimension being a dimension measured between diametrically opposite ends of a boundary defining the internal bore, the diametrically opposite ends being with reference to the center axis Υ '.

[0179] The transversal clearance dimension of the first engagement portion 242' increases gradually following the rate of change of a concave curvature as it extends axially away from the axial free end until reaching a maximum transversal clearance dimension at a maximum transversal clearance dimension plane, the maximum transversal clearance dimension plane being midway between the axial ends of the first engagement portion 242' in this example. The transversal clearance dimension of the first engagement portion 242' decreases gradually following the rate of change of a concave curvature as it extends axially away from the maximum transversal clearance dimension plane and reaches a third transversal clearance dimension plane having a third transversal clearance dimension where it joins with the second engagement portion 244' and defines a common boundary with the second engagement portion 244'. In this example, the first and third transversal clearance dimension are the same and define a minimum transversal clearance dimension.

[0180] The second engagement portion 244' has a first transversal clearance dimension at an axial level where it abuts with or meets the first engagement portion 242' to define the common boundary with the first engagement portion 242'. The transversal clearance dimension of the second engagement portion 244' increases gradually following the rate of change of a concave curvature as it extends axially away from the common boundary and the axial free end until reaching a maximum transversal clearance dimension at a maximum transversal clearance dimension plane, the maximum transversal clearance dimension plane being midway between the axial ends of the second engagement portion 244' in this example. The transversal clearance dimension of the second engagement portion 244' decreases gradually following the rate of change of a concave curvature as it extends axially away from the maximum transversal clearance dimension plane and the first axial free end and reaches a third transversal clearance dimension plane having a third transversal clearance dimension at a second axial free end of the building block 200. In this example, the first and third transversal clearance dimensions are the same and is a minimum transversal clearance dimension.

[0181 ] In this example, the maximum transversal clearance dimension plane of a connection portion is at an axial level which is intermediate two minimum transversal clearance dimension planes. The portion of the connection portion at or near a minimum transversal clearance dimension plane appears as a peripheral protrusion extending radially inwards from the main body. As the minimum transversal clearance dimension planes are at axial ends of the connection portion, each peripheral protrusion of the connection portion defines an entry aperture to the connection portion or an exit aperture from the connection portion and each peripheral protrusion defines an entry barrier to the connection portion or an exit barrier from the connection portion. Furthermore, rippled portions of adjacent connection portions intersect or cooperate to define a toothed peripheral portion protruding from the main body, as depicted in Figure 2A3, it will be appreciated that a toothed peripheral portion formed by cooperation of two abutting connection portions is stronger than a toothed peripheral portion formed at an axial free end of a connection portion. The concavely curved inner profile of the internal bore of the connection portion is adapted for closely fitted matching with the convexly curved outer profile of a male-type connection portion, such as the example male-type connection portions 142, 142B, 144, 144B, 146, 146B.

[0182] In some embodiments, the portion of the body between the protruding or toothed axial ends of a connection portion may be non-curved or may be substantially cylindrical. [0183] An example building block 200C depicted in Figures 2C1 to 2C4 comprises a main body 220C and an ensemble of connection portions 242C, 244C formed on the main body. The ensemble of connection portions comprises an example plurality of two engagement portions 242C", 244C". The axial lengths of the two engagement portions are identical and each engagement portion is symmetrical about its maximum lateral dimension plane NC-NC. The two engagement portions are not in abutment and are spaced apart by an elongate portion of the main body and the engagement planes of the two engagement portions not parallel but at an angle. Except for the aforesaid differences, the building block 200C is identical to the building block 200 and the description in relation to the building block 200 is incorporated herein by reference and applied mutatis mutandis, with numerals appended with a suffix "C". As depicted in Figure 2C2, the two engagement portions are joined in series on the main body, with adjacent engagement portions not in abutment and spaced apart by an elongate portion of the main body.

[0184] An example building block 300 comprises a main body 320 and an ensemble of connection portions 342, 344 formed on the main body, as depicted in Figures 3A1 to 3A3. The main body is an elongate bar made of a rigid and slightly resilient moldable material such as hard plastics and has a center axis C-C, which is also a longitudinal axis and a longitudinal center axis. The main body has a substantially uniform thickness along its length, with rounded ends at its longitudinal free ends and a substantially uniform width between the rounded ends. The ensemble of connection portions comprises an example plurality of two connection portions and the connection portions are distributed at different longitudinal locations along the length of the main body. The elongate bar has the shape of an elongate panel and comprises a first surface, a second surface, and a peripheral surface interconnecting the first and second surfaces. In this example, the first and second surfaces are parallel and the peripheral surface is orthogonal to the upper and lower surfaces and defines the thickness of the main body. In this disclosure, the first surface is also referred to as an upper surface or a top surface, and the second surface is also referred to as a lower surface or a bottom surface.

[0185] The connection portion is formed on the main body 320 and comprises an engagement portion 342', 344'. Each connection portion and each engagement portion has a center axis ψ1 , ψ2 which is also a coupling axis, along which the engagement portion and an engagement portion of a counterpart and matched connector will move relatively to each other to enter into coupled engagement. The center axes ψ1 , ψ2 of the connection portions are parallel and offset from each other and each center axis ψ1 , ψ2 is orthogonal to the longitudinal center axis C-C of the main body. In some embodiments, the center axis ψ1 , ψ2 is at a non-right angle to the center axis C-C of the main body.

[0186] The connection portion and the engagement portion 342', 344' is defined by an internal boundary wall of the main body. The internal boundary wall has an inner peripheral surface which extends about and along the center axis ψ1 , ψ2 to define an internal bore. The internal boundary wall, and hence the internal bore, is shaped to define a radial or peripheral indentation which retracts radially away from the center axis ψ1 , ψ2 into the main body as the internal boundary wall extends or progresses in an axial direction parallel to the center axis ψ1 , ψ2.

[0187] The inner peripheral surface of the main body faces and surrounds the internal bore and the center axis ψ1 , ψ2 and defines an inner boundary of the engagement portion. The inner boundary of the engagement portion is also the outer boundary of the internal bore and defines a clearance profile of the engagement portion or a clearance profile of the internal bore.

[0188] The inner peripheral surface extends around the inner periphery of the main body to define a distributed engagement means. The distributed engagement means is distributed around the interior of the main body and is adapted for making coupled engagement with a matched distributed engagement means of a counterpart connector having matching and compatible mating features.

[0189] The internal bore has an axial profile which defines an internal clearance profile of the engagement portion. The internal bore has a transversal clearance profile and a transversal clearance dimension at an axial level along the center axis ψ1 , ψ2. The transversal clearance profile and the transversal clearance dimension change as the internal bore extends in the axial direction of the center axis ψ1 , ψ2, and the internal bore has a non-uniform transversal clearance profile in the axial direction of the center axis ψ1 , ψ2, as that depicted in Figure 3A3.

[0190] The example engagement portion 342', 344' has a ripple-shaped portion which extends around the internal bore on the main body and is surrounded by the main body. The ripple-shaped portion has an inner surface having a ripple-shaped profile as it extends in the axial direction, the axial direction being parallel to the center the center axis ψ1 , ψ2. The ripple-shaped profile extends in the axial direction and is offset from the center axis the center axis ψ1 , ψ2. The inner surface having the ripple-shaped profile extends around the main body and about the center axis C-C to define the inner peripheral surface of the engagement portion.

[0191 ] The example ripple-shaped outer surface is concavely curved and the concavely curved inner surface is inward facing, that is, facing the internal bore and the center axis ψ1 , ψ2. The inward facing surface of the example engagement portion is the inner peripheral surface of the main body which extends around the internal body and is circularly symmetrical about the center axis ψ1 , ψ2. In a perspective, the inner peripheral surface of the main body can be considered as being formed by revolving the concavely curved inward facing surface for 360 degrees about the center axis ψ1 , ψ2 following a circular path.

[0192] As the inner surface of the example engagement portion has a ripple-shaped profile in the axial direction, the transversal clearance dimension of the engagement portion changes as the engagement portion extends in the axial direction, the transversal clearance dimension being a transversal dimension measured in a direction orthogonal to the center axis ψ1 , ψ2. More specifically, the transversal clearance dimensions vary between a maximum clearance dimension providing a maximum transversal clearance and a minimum clearance dimension providing a minimum transversal clearance.

[0193] The engagement portion has a first transversal clearance dimension at an axial level of the top surface of the main body. The transversal clearance dimension is a dimension measured at an axial level between diametrically opposite ends of a boundary defining the internal bore, the diametrically opposite ends being with reference to the center axis ψ1 , ψ2. The transversal clearance dimension of the engagement portion increases gradually following the rate of change of a concave curvature as it extends axially away from the top surface until reaching a maximum transversal clearance dimension at a maximum transversal clearance dimension plane, the maximum transversal clearance dimension plane being midway between the top and bottom surfaces of the main body in this example. The transversal clearance dimension of the engagement portion decreases gradually following the rate of change of a concave curvature as it extends axially away from the maximum transversal clearance dimension plane and the top surface and reaches a third transversal clearance dimension plane having a third transversal clearance dimension at the bottom surface of the main body. In this example, the first and third transversal clearance dimensions are the same and is a minimum transversal clearance dimension.

[0194] The transversal clearance dimension of the engagement portion increases gradually following the rate of change of a concave curvature as it extends axially away from the axial free end until reaching a maximum transversal clearance dimension at a maximum transversal clearance dimension plane, the maximum transversal clearance dimension plane being midway between the axial ends of the engagement portion in this example. The transversal clearance dimension of the first engagement portion 342' decreases gradually following the rate of change of a concave curvature as it extends axially away from the maximum transversal clearance dimension plane and reaches a third transversal clearance dimension plane having a third transversal clearance dimension where it joins with the second engagement portion 344' and defines a common boundary with the second engagement portion 344'. In this example, the first and third transversal clearance dimension are the same and define a minimum transversal clearance dimension. In some embodiments, the first and third transversal clearance dimensions are different.

[0195] The portion of the engagement portion at or near a minimum transversal clearance dimension plane appears as a peripheral protrusion extending radially inwards from the main body. As the minimum transversal clearance dimension planes are at axial ends of the engagement portion, each peripheral protrusion of the engagement portion defines an entry aperture or exit aperture of the engagement portion and each peripheral protrusion defines an entry barrier to the engagement portion or an exit barrier from the engagement portion. The concavely curved inner profile of the internal bore of the engagement portion is adapted for closely fitted engagement with the convexly curved outer profile of a male-type connection portion, such as the example male- type connection portions 142, 142B, 144, 144B, 146, 146B.

[0196] In general, the connection portion, and hence the engagement portion 342', 344', has same features as those of the connection portions of the building block 200, 200B, 200C, 200D, and the engagement portion 342', 344' has the features of the engagement portions 242', 244', or 246B', except that the center axis of the engagement portion 342', or 344' is orthogonal to the longitudinal center axis C-C and the coupling direction is orthogonal to the longitudinal center axis C-C. Furthermore, the engagement plane of each engagement portion and the longitudinal axis C-C are parallel.

[0197] Except for the aforesaid differences, the description in relation to the building block 200 is generally applicable to the building block 300 and the description is incorporated herein by reference where the context permits and applied mutatis mutandis.

[0198] As depicted in Figure 3A1 , the two engagement portions are in series connection, with adjacent engagement portions separated.

[0199] An example building block 300B comprises a main body 320B and an ensemble of connection portions formed on the main body, as depicted in Figures 3B1 to 3B3. An example plurality of eight engagement portions 341 B', 342B', 348B' is formed on the main body and the main body has square corners at its longitudinal ends. Except for the aforesaid differences, the building block 300B is identical to the building block 300 and the description in relation to the building block 300 is incorporated herein by reference and applied mutatis mutandis, with reference numerals appended with a suffice "B". As depicted in Figure 3B1 , the engagement portions are in series connection, with adjacent engagement portions separated.

[0200] An example building block 300C comprises a main body 320C and an ensemble of connection portions 340C formed on the main body, as depicted in Figures 3C1 to 3C3.

[0201 ] An example plurality of eight engagement portions 341 C, 342C, 348C is formed on the main body and the main body has a curved longitudinal axis CC-CC. Except for the aforesaid differences, the building block 300C is identical to the building block 300 and the description in relation to the building block 300 is incorporated herein by reference and applied mutatis mutandis, with reference numerals appended with a suffice "C". As depicted in Figure 3C1 , the engagement portions are in series connection, with adjacent engagement portions separated.

[0202] An example building block assembly 400 comprises a plurality of building blocks of the aforesaid types connected together, as depicted in Figures 4A1 to 4A3. This example building block comprise two axially aligned example building blocks 200 which are mounted on axial ends of an example building block 100. The example building block 100 serves as a male-type interconnector or an interconnecting block interconnecting the two building blocks 200. As depicted in Figure 4A3, one of the two female-type engagement means of the building block 200 on top is in coupled engagement with a top male-type engagement means of the building block 100, and one of the two female-type engagement means of the building block 200 on bottom is in coupled engagement with a bottom male-type engagement means of the building block 100.

[0203] An example building block sub-assembly 400B comprises a plurality of building blocks of the aforesaid types connected together, as depicted in Figures 4B1 to 4B3. This example building block comprise two axially aligned and stacked example building blocks 100. The stacked building blocks are interconnected by an example building block 200. As depicted in Figure 4B3, one of the two female-type engagement means of the building block 200 is in coupled engagement with a top male-type engagement means of the building block 100, and the other one of the two female- type engagement means of the building block 200 is in coupled engagement with a bottom male- type engagement means of the building block 100.

[0204] An example building block sub-assembly 500 is constructed from a plurality of building blocks, as depicted in Figures 5A1 to 5A3. The example building block sub-assembly 500 comprises a first building block 300' which is constructed according to the building block 300, a second building block 300" which is an elongated version of the building block 300, and a third building block 100C which is constructed according to the building block 100C. The example building block 100C serves as a male-type interconnector or an interconnecting block interconnecting the two building blocks 300', 300". The building block 100C while functioning as an interconnection means also forms a live pivot joint and the building block 300', 300" are relatively rotatable about the building block 100C as a pivot hinge.

[0205] As depicted in Figure 5A3, one of the two female-type engagement means of the building block 300' is in coupled engagement with a top male-type engagement means of the building block 100C, and one of the two female-type engagement means of the building block 300" is in coupled engagement with a bottom male-type engagement means of the building block 100C.

[0206] To detach the building block sub-assembly 500, a user only need to pull the first and third building blocks apart in an opposite direction to the coupling direction or to push the interconnecting block out of coupled engagement with the first and third building blocks.

[0207] An example building block sub-assembly 500B is constructed from a plurality of building blocks, as depicted in Figures 5B1 to 5B3. The example building block sub-assembly 500B comprises a plurality of building blocks 300" which are stacked and interconnected by a plurality of interconnecting blocks of the type 100, 100B, 100C, 100D, or their variations without loss of generality.

[0208] An example building block sub-assembly 500C is constructed from a plurality of building blocks, as depicted in Figures 5C1 and 5C2. The building block sub-assembly 500C comprises one building block which is constructed according to the features of the building block 100, one building block which is constructed according to the features of the building block 100C, one building blocks which is constructed according to the features of the building block 200 and one building block which is constructed according to the features of the building block 200C. The building block 100 is connected to one longitudinal end of the building block 200C, the building block 100 is connected to another longitudinal end of the building block 200C distal to the building block 100, and the building block 200C is connected to a longitudinal end of the building block 100 not connected to the building block 200C. In this sub-assembly, the building block 100 is rotatable about its coupling axis relative to the building block 200C, and the building block 200 is rotatable about its coupling axis relative to the building block 200C. It would be appreciated that each of the component building blocks 100, 100C, 200 can be an integral part of a building block without loss of generality. For example, the component 200C can be an integral part of the building block 300, 300B, 300C etc.

[0209] An example building block sub-assembly 500D is constructed from a plurality of building blocks, as depicted in Figures 5D1 and 5D2. The building block sub-assembly 500D comprises three building blocks each of which is constructed according to the features of the building block 300C, one building block which is constructed according to the features of the building block 100 and one building block which is constructed according to the features of the building block 100C. Referring to the Figures, two of the building blocks 300C are joined together at their longitudinal ends by means of the building blocks 100 and 100C, and one third building block 300C has one of its longitudinal ends joined at a joined end of the two building blocks 300C and the third building block 300C is pivotally movable relative to the sub-assembly of the two doubly joined building blocks 300C. The building block 100C having three connection portions functions as a live pivot hinge as well as a live interconnector block joining the three building blocks.

[0210] An example building block sub-assembly 500E is constructed from a plurality of building blocks, as depicted in Figures 5E1 to 5E4. The building block sub-assembly 500E comprises three building blocks each of which is constructed according to the features of the building block 300C and a plurality of building blocks constructed according to the features of the building blocks 100, 200. Referring to the Figures, all the three building blocks 300C are joined together at one their longitudinal ends by means of an assembly of building blocks selected from the building blocks 100, 200. All the third building blocks 300C are pivotally movable relative to the sub-assembly of interconnectors formed from the building blocks 100, 200.

[021 1 ] The example building block is make of a thermoplastic which is rigid or semi-rigid and having a small degree of resilience to facilitate snap-fit connection. While the building blocks or the connection portions thereof are intended to be snap-connected without the need of permanent fasteners such as screws, additional use of such fasteners to enhance structural robustness is possible. In general, the building blocks or the connection portions may also be made of metal or other moldable materials that are rigid or semi-rigid and having a small resilience.

[0212] A building block assembly disclosed herein may comprise a first building block, a second building block and a third building block in detachable connection is disclosed. The first building bock comprises a first main body on which a first engagement means is formed, the first engagement means having a first center axis defining a first coupling axis, a first coupling direction parallel to first coupling axis and a first engagement plane orthogonal to the first coupling axis. The second building bock comprises a second main body on which a second engagement means is formed, the second engagement means having a second center axis defining a second coupling axis, a second coupling direction parallel to second coupling axis and a second engagement plane orthogonal to the second coupling axis. The third connection block is an interconnection block comprising a third main body having a longitudinal axis and an interconnection means adapted for interconnecting the first building block and the second building block. The interconnection means comprises a plurality of engagement devices including a first engagement device and a second engagement device. The first engagement device has a first engagement axis for making interconnection with the first building block upon by relatively moving the first building block and the third building block along the first coupling direction. The second engagement device has a second engagement axis for making interconnection with the second building block upon by relatively moving the second building block and the third building along the second coupling direction. The interconnection means comprises a live hinge joint interconnecting the first building block and the second building block.

[0213] A building block comprising a main body and a plurality of connection portions on the main body is disclosed. The connection portions may be distributed along a center axis of the main body and each connection portion comprises an engagement portion. Each engagement portion comprises a rippled portion may have a rippled profile extending along a coupling direction defined by a coupling axis which is coaxial with the center axis and the rippled profile revolves about the center axis in a direction orthogonal to the center axis to define an engagement plane which is orthogonal to the coupling direction. Each engagement portion may comprise a rippled portion having a rippled profile extending along a coupling direction defined by a coupling axis which is orthogonal to the center axis and the rippled profile revolves about the coupling axis in a direction orthogonal to the center axis to define an engagement plane which is orthogonal to the coupling direction.

[0214] The first engagement device of the interconnection block may comprise a ripple-shaped peripheral surface which extends about the first engagement axis portion and which has a ripple- shaped profile on extending along an axial direction parallel to the first engagement axis to define a ripple shaped engagement portion.

[0215] The second engagement device of the interconnection block may comprise a ripple- shaped peripheral surface which extends about the second engagement axis and which has a ripple-shaped profile on extending along an axial direction parallel to the second engagement axis portion to define a ripple shaped engagement portion. The ripple shaped engagement portion is formed inside the third main body to define a female-type engagement portion.

[0216] The ripple shaped engagement portion may be formed on an outer periphery of the third main body to define a male-type engagement portion. [0217] The first engagement device of the interconnection block may comprise a first inner engagement portion having the first engagement axis as a coupling axis and a first outer engagement portion which is coaxial with and surrounds the first inner engagement portion.

[0218] The second engagement device of the interconnection block may comprise a second inner engagement portion having the second engagement axis as a coupling axis and a second outer engagement portion which is coaxial with and surrounds the second inner engagement portion.

[0219] The first inner engagement portion may comprise a first ripple-shaped inner peripheral surface which is formed inside the third main body and extends about the first engagement axis to define a first internal bore having a first ripple-shaped inner profile on extending along an axial direction parallel to the first engagement axis to define a ripple shaped female-type engagement portion. The first outer engagement portion comprises a first ripple-shaped outer peripheral surface which is formed on a first outer periphery of the third main body and extends about the first engagement axis, the first ripple-shaped outer peripheral surface having a first ripple-shaped outer profile on extending along an axial direction parallel to the first engagement axis to define a ripple shaped male-type engagement portion.

[0220] The second inner engagement portion may comprise a second ripple-shaped inner peripheral surface which is formed inside the third main body and extends about the second engagement axis to define a second internal bore having a second ripple-shaped inner profile on extending along an axial direction parallel to the second engagement axis to define a ripple shaped female-type engagement portion. The second outer engagement portion comprises a second ripple-shaped outer peripheral surface which is formed on a second outer periphery of the third main body and extends about the second engagement axis, the second ripple-shaped outer peripheral surface having a second ripple-shaped outer profile on extending along an axial direction parallel to the second engagement axis to define a ripple shaped male-type engagement portion.

[0221 ] In some embodiments, the third main body is elongate and has a longitudinal center axis. The first engagement device and the second engagement device are at different longitudinal locations on the elongate third main body.

[0222] In some embodiments, the interconnection means is to connect the first building block and the second building block such that the first main body and the second main body are in abutment.

[0223] In some embodiments, the first main body is an elongate bar extending along a longitudinal center axis and the live hinge joint has a pivot axis which is orthogonal to the a first longitudinal center axis. The second main body is an elongate bar extending along a second longitudinal center axis and the live hinge joint has a pivot axis which is orthogonal to the longitudinal center axis. The third main body is an elongate bar extending along a third longitudinal center axis to define a hinge axis of the live hinge joint.

[0224] In some embodiments, the hinge axis is orthogonal to both the first longitudinal center axis and the second longitudinal center axis.

[0225] In some embodiments, the live hinge joint is a live pivot hinge and the second building block and the second building block are relative rotatable about the live pivot hinge.

[0226] In some embodiments, the first engagement device is a first snap-fit fastener part and the second engagement device is a second snap-fit fastener part compatible or matched with the first snap-fit fastener part.

[0227] In some embodiments, the first coupling axis and the second coupling axis are coaxially aligned, and the longitudinal axis of the third main body is orthogonal to the first coupling axis or the second coupling axis.

[0228] In some embodiments, the first engagement axis and the second engagement axis are coaxially aligned or at an angle.

[0229] In some embodiments, a plurality of ripple-shaped engagement portions is formed on the third main body and the ripple-shaped engagement portions are distributed in a length direction extending along the longitudinal axis of the third main body. Adjacent ripple-shaped engagement portions are in abutment and intersection.

[0230] In some embodiments, the adjacent ripple-shaped engagement portions which are in abutment intersect to form a peripheral tapered indentation or a tapered peripheral protrusion.

[0231 ] In some embodiments, the engagement portion comprises a protruding portion which projects radially away from a center axis of the main body or which projects axially away from the main body along the coupling direction to define a ripple-shaped protrusion to function as a male- type engagement portion or a male-type connector. The engagement portion comprises an indentation which is retracted radially away from center axis of the main body or which is retracted axially along the coupling direction into the main body to define a ripple shaped receptacle to function as a female type engagement portion or a female type connector.

[0232] In some embodiments, the rippled portion follows a circular path or a regular polygonal path having rounded corners when extending around the main body. [0233] In some embodiments, the connection portion is integrally formed on the main body.

[0234] In some embodiments, the main body is rigid and formed of a rigid yet slightly resilient materials such as hard plastics.

[0235] In some embodiments, the main body is in the shape of an elongate bar with one connection portion or a plurality of connections formed and distributed along its length, for example, along its longitudinal center axis.

[0236] In some embodiments, one connection portion or a plurality of connections is formed along a coupling axis of the connection portion.

[0237] In some embodiments, the main body is in the shape of an elongate bar. The elongate bar may be solid and has a rectangular, polygonal, circular or oval cross-section.

[0238] In this disclosure, coupled engagement means tight-fit or closely-fit engagement, including, friction fit, press fit, interference fit, and snap-fit engagement.

[0239] While the disclosure has been described with reference to examples and embodiments, the examples and embodiments are not meant to be restrictive and should not be used to limit the scope of disclosure.

[0240] For example, the example building blocks herein are toy building blocks for toy or toy-like applications and the building block assemblies are toy or toy-like building block assemblies. However, the building blocks herein can also be non-toy building blocks such as machine building blocks, construction building blocks such as tiles or bricks, and/or other industrial building blocks and the building block assemblies are modular built machines or machine parts, modular built structures, modular built structure parts, modular built structural parts, modular built fixture and/or fixture parts and/or fixture sub-assemblies.

[0241 ] When used for toy applications as toy assemblies, the component building blocks have a typical radial extent (or width, or lateral extent) of between 1 cm and 15cm and a typical axial extent (or thickness) or between 0.3mm for a miniature block to 5cm. For example, the radial extent can be, in units of cm, 1 for a miniature block, 1 , 1 .5, 2, 2.5, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 1 1 , 1 1 .5, 12, 12.5, 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5, 20, or more for a mega block, or a range or any ranges formed by a selected combination of any of the aforesaid values as limits of a range or limits of ranges. For example, the axial extent can be, in units of cm, 1 for a miniature block, 1 , 1 .5, 2, 2.5, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, or more for a mega block, or a range or any ranges formed by a selected combination of any of the aforesaid values as limits of a range or limits of ranges. [0242] When for industrial uses, for example for modular construction of machines, buildings, structures, parts, the aforesaid values may be scaled up, in unit of times, by 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 1 10, 120, or a range or any ranges formed by a selected combination of any of the aforesaid values as limits of a range or limits of ranges; and the component building blocks may be made of strong thermoplastics, carbon fibres, fibre glass, or metals, or other mouldable materials, having a high rigidity and a small degree of resilience.

[0243] While assemblies of the building blocks have been described with reference to snap engagement or snap connection and snap connectors, the building blocks may be joined or connected by other press-fit mechanisms or methods without loss of generality.

[0244] While the example connectors described and depicted herein are snap connectors adapted for making snap-fit engagement, a connector herein can be a "press-fit" connector for making press-fit engagement or a "friction-fit for making press-fit engagement unless the context requires otherwise.

[0245] In general, a snap-fit connector comprises an engagement portion having snap-fit mating features. The terms "snap", "snap fit", and "snap-fit", are interchangeably used herein unless the context requires otherwise. The terms "fastener" and "connector" are also interchangeably used herein unless the context requires otherwise. In this description and specification, and when in relation to a connector or an engagement portion having a coupling axis, the terms "closely-fitted engagement" and "coupled engagement" are interchangeable, the axial direction is with respect to the coupling axis and the axial direction is along the coupling axis, and the radial direction is with respect to the coupling axis and the radial extent is in the radial direction, unless the context requires otherwise.

[0246] The words "first", "second", "third", "fourth", etc. are generic terms for ease of reference only and are not intended for indicate priority, order or sequence unless the context requires otherwise or specifies otherwise. Where there are conflicts in relation to the aforesaid generic terms, the conflicts are to resolve to give a meaning which is reasonable for interpretation where possible.

[0247] While singular and plural terms are used herein, a singular term may apply mutatis mutandis to a plural situation and a plural term may apply mutatis mutandis to a single situation where the context permits or requires. ble of numerals

Building block 120 Core portion

First connection portion 144 Second connection portion

Third connection portion