From the mid sixties through the seventies he continued the experimentation in prints by printing onto aluminum, moving plexiglass disks, clothes, and other surfaces. He challenged the view of the artist as auteur by assembling engineers to help in the production of pieces technologically designed to incorporate the viewer as an active participant in the work. He also created performance pieces centered around chance. To watch dancers on roller-skates (”Pelican”, 1963) or to hear the sound of a gong every time a tennis ball was hit (”Open Score”, 1966), was to witness an art that exchanged lofty ambitions for a sense of excitement and playfulness while retaining meaning.