A 3-dimensional assembly is constructed from three 2-dimensional pieces.
Each piece is formed with two slots such that the pieces are operatively
identical and are interchangeable, and such that the pieces may be formed
into a structure without bending of the pieces, and such that the pieces
do not all share a common line of intersection. The resulting
3-dimensional structure may be used as a toy, puzzle, ornament,
engineering structure, etc.