Circle, 2015 (left)
Two set squares
The eponymous circle is created from the two semi-circles printed on the each of the two geometric set squares (or set triangles in American usage) that are placed together, in fact forming a square.
Garbage Bag, 1996 (right)
Black plastic garbage bag, air, twist tie
Tied shut and apparently full, a garbage bag is placed close to a doorway. It is filled with air.
Photo © Andrea Rossetti