Patent US 4,597,579

Six physically interchangeable pieces, each corresponding to a pair of adjacent cube edges, have surfaces that allow them to be assembled into subassemblies which, in turn, slide together to create a substantially symmetrical shape. Three fundamentally distinct arrangements of the pieces are possible, each having many possible sequences of assembly. In the final assemblies, the pieces are held together by mutually generated friction, but subassemblies of pieces slide along any of three orthogonal axes. Many external shapes are possible. Varied surface treatments, creating recognizable patterns on the final assemblies, add another significantly higher level of difficulty in these puzzles. One embodiment has holes that make it useful as an organizer on a desk.