Mary Martin showed a number of related relief constructions in an exhibition in early 1964. The common unit to all of them was a right-angled wedge. Made from a cube of wood cut diagonally in half, the wood surfaces were covered in a thin sheet of stainless steel. They are grouped together against a background of black formica. The wedges are juxtaposed in all possible ways so as to reflect the light from different angles. The complexity of the reflections and light patterns becomes clear only as the spectator moves his or her position, or the angle of light changes.