Three out of six surfaces of the cube are made of flexible membrane (foil mirror) with air tank and a compressor connected to it and the other three mirrors are semi transparent spy-glass. By inflating or deflating the air tank, the membrane turns convex or concave, deforming the reflections.
Gorgeous! Instead of using a compressor, I think it would have been interesting to add linear actuators to each of the three flexible membranes so that more complex patterns could have been created. Alternative lighting schemes would have been interesting, too.