IL COMMUTATORE, 1970.
From the Disequilibrating System – a comprehension model.

This unusual tool is in a way the hallmark of all La Pietra’s explorations of the urban environment. La Pietra has used it many times to see things that were not immediately apparent; he often had other people use it, too. It is a means of exploring and developing ideas, a tool developed at a time when “radical design” was constructing elusive, utopian objects.