Background Many types of three-dimensional foldable devices used as novelty pieces, puzzles and games are known and include flexagons and origami. Flexagons are paper polygons, folded from straight or crooked strips of paper or thin cardboard, which have the property of changing their faces when they are flexed. There are various types of flexagons, such as hexaflexagons and tetraflexagons. A good description of hexaflexagons is found in chapter one of a book entitled"Mathematical Puzzles and Diversions"by Martin Gardner, published by Penguin Books in 1975.

Other known prior art includes US Patent No. 3,962, 816 (Sarid) entitled"Foldable Structure ", US Patent No. 4,429, 878 (Asao) entitled"Foldable Puzzle Cards ", US Patent No. 5,564, 704 (Yang) entitled"Paper Folding Game for Spatial Puzzle ", US Patent No. 5,735, 520 (Matos) entitled"Fold-through Picture Puzzle ", and US Patent No. 5,759, 328 (Richwine et al.) entitled"Multi-sided Novelty Piece and method for making the same". Much of this art is essentially two-dimensional in nature and the devices described can be folded to rearrange the order of their internal shapes but not to change the exterior shape or form three-dimensional objects. Some of this prior art is adapted to allow for the formation of three-dimensional objects, however such objects cannot be continually folded, or can only be folded in one direction either backwards or forwards. Some of these prior art documents describe objects which can be continually folded but not connected with like objects.

It is preferred that the present invention may provide a device that can be continually folded in several directions to form three-dimensional objects, and loosely connected to other such devices to form more complex three-dimensional objects. Preferably, the device of the present invention may be constructed from irregular shapes and form irregular 3-dimensional objects.

Summary of Invention In one aspect the present invention is a foldable sheet device comprising at least first and second layers of sheet material superimposed one upon the other, each layer comprising more than two shapes, wherein each shape of the first layer is connected to two adjacent shapes of the second layer, and each shape of the second layer is connected to two adjacent shapes of the first layer, and wherein each shape can be folded about at least two fold axes.

Preferably the device can be folded about said fold axes to manipulate the device into a plurality of three-dimensional configurations.

Preferably when the device is in a three-dimensional configuration it is stackable with other similar devices to form a larger three-dimensional object.

Preferably the device is stackable with one or more other devices in a horizontal or vertical relationship.

Preferably in one embodiment each shape of the first layer is connected to at least two shapes of the other layer in a region between one of said fold axes and the periphery of the layers.

In another embodiment the sheet material is a flexible material and the fold axes are formed within the sheet material. Preferably the sheet material is paper or cardboard.

In yet another embodiment the device is a novelty piece having pictures, pattern or indicia on at least one of said shapes. Preferably in use when said device is folded about one or more of said fold axes, the picture, pattern or indicia on at least one of said shapes forms a larger picture, pattern or indicia in combination with the picture, pattern or indicia of at least one of the other shapes.

Preferably said device is a novelty piece having a picture, pattern or indicia on at least one of its said shapes, and when in stacked relationship with other similar devices to form a larger three-dimensional object the picture, pattern or indicia on said at least one shape forms part of a larger picture, pattern or indicia of the larger three- dimensional object.

In yet another embodiment the sheet material is a rigid material and the fold axes are formed by hinge joints. Preferably the device may be a piece of furniture able to support a further member.

In a further embodiment of the device, a further shape is able to be foldably or hingedly connected to at least one of the shapes of one of said layers.

In yet still a futher embodiment the shapes of each plane are polygonal. Preferably the polygonal shapes are rhombs.

In yet still a futher embodiment the shapes of each plane are polygons and are disposed adjacent to each other to form a hexagon or an octagon.

In a second aspect the present invention consists in a foldable device comprising first and second layers each of which comprises a plurality of adjacent sheet material shapes, each said layer of sheet material shapes being disposed to form a polygon, the first layer is connected to the second layer at a plurality of joint locations such that the device can be folded about a plurality of fold axes to manipulate the device into a plurality of configurations.

In a third aspect the present invention is a foldable sheet device comprising at least first and second sets of sheet material, said first set of sheet material comprising more than two shapes, and said second set of sheet material comprising more than two shapes, wherein each shape of said second set is connected to two adjacent shapes of said first set, and each shape of said first set is connected to two adjacent shapes of said second set, and wherein each shape of both said first and second sets can be folded about at least two fold axes.

Preferably at least a portion of two shapes of one of the sets of sheet material overlap.

Brief Description of Drawings The present invention will now be described by way of example with reference to the following drawings.

Fig. 1 is an exploded isometric view of a first embodiment of the foldable device of the present invention consisting of two, upper and lower, hexagonal planes of paper.

Fig. 2 is a plan view of the foldable device of Fig. 1.

Fig. 3 is a bottom view of the foldable device of Fig. 1.

Figs. 4-7 show perspectives of the foldable device of Fig. 1 in progressive opening up and folding of the device to form a three-dimensional object.

Fig. 8 shows three of the foldable devices of Fig. 1 in three-dimensional configurations stacked in a horizontal relationship.

Fig. 9 shows a second embodiment of three foldable devices of the present invention in a three-dimensional stacked configuration stacked in a horizontal relationship.

Fig. 10 shows a plan view hexagonal template for constructing the foldable devices of the first and second embodiments.

Fig. 11 shows a plan view of an octagonal template for constructing a third embodiment of the foldable device of the present invention.

Mode of Carrying Out Invention Figs. 1-3 depict a first embodiment of a foldable device made up of six rhomb (diamond) shaped pieces of paper 1-6. The foldable device may be of the type used as a novelty or puzzle. Each rhomb piece 1-6 may have a picture, pattern or indicia (not shown) printed on each side thereof. Three of the rhomb shaped pieces of paper 1,2, 3 form a first (upper) hexagon plane which is parallel to a second (lower) hexagon plane made up of the other three rhomb shaped pieces of paper 4,5, 6. Each rhomb shaped piece of paper 1,2, 3 is foldable about two fold axes (flexible joints) shown by dashed lines which form a triangle 7, whilst each rhomb shaped piece of paper 4,5, 6 is foldable about dashed lines (flexible joints) which form a triangle 8. The first hexagon plane made up of rhomb shaped pieces of paper 1,2, 3 is aligned with the second hexagon made up of rhomb shaped pieces of paper 4,5, 6 and glued together at the six shaded triangular areas 9-14.

Referring now to Figures 4 and 5, this first embodiment of the foldable device can have its first hexagonal plane of rhomb shaped pieces of paper 1-3 folded out about the dashed lines 8 to reveal the picture, pattern or indicia on the rhomb shaped pieces in a different configuration.

Referring now to Figs. 6 and 7 this first embodiment of the foldable device can be further folded out to create a self supporting 3-dimensional object which can be stacked with other such devices as shown in Fig. 8, and can cooperatively display a picture, pattern or indicia.

The foldable device of this first embodiment can be folded continually in many directions to get to the original shape shown in Fig 1, and can also be folded to form

different shape and picture combinations, other than those shown in the figures which can be loosely stacked or connected horizontally.

Fig. 9 depicts a second embodiment of three foldable devices 50 in a horizontal stacked relationship. each of the devices 50 have a different picture portion 51,52 and 53 which cooperatively form a larger picture.

Referring now to Fig. 10, a regular hexagonal template for constructing the foldable device is shown. The hexagon having vertices 21-26 and midpoints 27-32.

Proceeding in a clockwise direction, lines 41,42 and 43 are drawn connecting point 27 with point 29, point 29 with point 31 and point 31 with point 27, respectively. These lines 41,42 and 43 define the location of the primary flexible joints (fold axes) of the first hexagonal plane. Proceeding in a clockwise direction, lines 44,45 and 46 are drawn connecting point 28 with point 30, point 30 with point 32 and point 32 with point 28, respectively. These lines 44,45 and 46 define the location of the primary flexible joints (fold axes) of the second hexagonal plane. Two internal triangles are formed by this method. The intersection of the two triangles forms a third internal hexagon having vertices 33-38. From these construction lines a number of shapes can be defined. One typical shape in a plane has a maximum polygonal boundary defined by points 21,22, 28,36, 37,32 and a minimum polygonal boundary defined by the line spanning points 33,34. The outer border of a typical shape may lie along a closed line of 39 that lies within the maximum polygonal boundary and outside the minimum polygonal boundary.

The first shape in the first hexagonal plane has a maximum polygonal boundary defined by points 21,22, 28,36, 37,32 and primary flexible joints, which lie along the lines defined by points 27,35 and 27,38. The second shape in the first hexagonal plane has a maximum polygonal boundary defined by points 23,24, 30,38, 33,28, and primary flexible joints which lie along the lines defined by points 29,34 and 29,37. The third shape in the first hexagonal plane has a maximum polygonal boundary defined by points 25,26, 32,34, 35,30 and primary flexible joints, which lie along the lines defined by points 31,36 and 31,33. The first shape in the second hexagonal plane has a maximum polygonal boundary defined by points 22,23, 29,37, 38,27 and primary flexible joints, which lie along the lines defined by points 28,33 and 28,36. The second

shape in the second hexagonal plane has a maximum polygonal boundary defined by points 24,25, 31,33, 34,29 and primary flexible joints which lie along the lines defined by points 30,38 and 30,35. The third shape in the second hexagonal plane has a maximum polygonal boundary defined by points 26,21, 27,35, 36,31 and primary flexible joints which lie along the lines defined by points 32,34 and 32,37. Other flexible joints (or fold axes) can be positioned within any of the shapes to enable a greater number of three dimensional configurations to be achieved upon folding of the device. The first and second plane are joined (or glued) together within the six polygons defined by points 21,27, 33,32 ; 27,22, 28,34 ; 28,23, 29,35 ; 29,24, 30,36 ; 30,25, 31,37 and 31,26, 32,38.

It should be understood that the principle behind the generation for template shown in Figure 10 can be extended to a polygonal foldable device having first and second polygonal planes. The polygon may be regular or irregular in shape, but must have an even number of sides. The template for constructing the polygon having an even number is drawn. A mid-point is placed at the centre of each side. Proceeding in a clockwise direction a line is drawn connecting the first mid-point, to the third mid-point, the third to the fifth, and so on until the first mid-point is reached again, wherein the lines define the locations of the primary flexible joints (fold axes) in the first (upper) polygonal plane, and the position of shapes in the second (lower) plane. Proceeding in a clockwise direction a line is drawn connecting the second mid-point, to the fourth mid-point, the fourth to the sixth, and so on until the second mid-point is reached again, wherein the lines define the locations of the primary flexible joints in the second (lower) polygonal plane, and the position of shapes in the first (upper) polygonal plane. Two internal polygons are formed by this process, each with half the number of sides of the original polygon. The intersection of the two internal polygons forms a third internal polygon with the same number of sides as the original polygon. From these various construction lines a number of shapes, corresponding to the number of sides of the original polygon, and their positions, and the position of several flexible joints, can be defined. These are then used as templates to cut mould or form solid materials into the same shapes, create flexible joints at defined locations, and position them into two parallel planes which are then joined at points defined by the template.

Additionally in a further embodiment, several incisions and holes may preferably be cut inside each shape's outer borders, and they may also have several other layers of shapes attached to their surfaces, such that the layers may be folded back from the main shapes.

Fig. 11 depicts a template produced from a regular octagon, and the maximum boundary and position of the first shape in the upper plane, defined by the points 101, 102,110, 120,121, 122,123, 116 and the location of primary flexible joints (fold axes) that lie along lines 109,119, and 109,124. A similar method of construction applies to other even sided polygons either regular or irregular.

Whilst the first embodiment shown in Figs. 1-3 refers to a foldable device made of paper or thin cardboard, it may in another embodiment be made of a rigid sheet material such as wood, plastic or metal and hinged joints are used rather than flexible joints to connect the various polygonal shapes. Preferably such a rigid sheet device may in a specific three-dimensional configuration be able to be used as a furniture piece or component to support a separate table top or other member, either by itself or in combination with other such devices.

It should be obvious to those skilled in the art that numerous variations and modifications could be made to the foldable device without departing from the spirit and scope of the invention.