study for 2 rectangular glass panels, set in motion, 1990 - pencil sketch 12 x 10 cm
study for rotating glass disc, 1990 - blue ballpoint sketch 19 x 12,5 cm
study for rotating glass disc, 1990 - black ballpoint sketch 17 x 11,5 cm
study for rotating glass disc, 1990 - pencil sketch 13,5 x 11 cm
Zonder titel/Untitled, 1990 - glass disc mounted on an electric motor (the center of rotation is eccentric, giving the disc a sort of wobbling motion)