the 70's Gene Gill painted abstract designs on several layers of clear
plastic. Each layer was set into a frame and spaced 1" apart. The
background was a sheet of polished aluminum, also spaced 1" from the sheets
of plastic. All this was set into a polished aluminum frame.
The image constantly changed as the viewer moved around and as the lighting
changed. This website features some of these works, plus screen prints
that the artist created during the same period.