Here is a mask of Charlie Chaplin that rotates. Notice that, no matter how hard you try, the hollow and concave rear of the mask eventually becomes a convex golden face that spins counterclockwise. Pretty cool, give it a try:

Haven’t done a brain art post in a while, so figured I’d put up some pictures of Felice Varini’s incredible work. Note that these images were not ‘photoshopped’, nor do they use painted glass.