The Squarcle is a 3D optical illusion based on the work of Kokichi Sugihara (as seen at https://www.youtube.com/watch?v=oWfFco7K9v8)

I was so intrigued after watching that that I was compelled to try to replicate it myself! It has taken multiple attempts and several revisions, and I am now happy to present it here.

I have included 2 STL's, one with a mirrored bottom that enhances the illusion but requires supports, and one with a flat bottom that is easier to print.