PURPOSE: To obtain free combination by applying irregular machining to the necessary portion of a member and utilizing formed recesses and projections so that irregularly machined members or the irregularly machined member and the unmachined member can be connected, separated, rotated, and moved for functional changes.

CONSTITUTION: Irregular machining is applied to the necessary portion on the surface of a member such as a plate, and a circular projection 10 is inserted into a circular recess 11 for connection. Or, a circular projection 10 is supported by circumscribing four points on other circular projections for connection. Various connecting methods are considered using these two methods as a basis. For example, circular projections 10 are formed on the wide face 14 of a member, circular recesses 11 are formed on the narrow face 13 on four sides, the wide face 14 and the narrow face 13 are connected, or the wide face 14 and the wide face 14 are connected. In this case, the center line of the narrow face 13 indicates that two integrally molded and irregularly machined members are stuck in the thickness direction. A sheet of member irregularly machined on the surface and the rear is obtained accordingly.