I found a picture of this online but couldn't find the instructions on how it was built. With some trial and error, I recreated the illusion. Can you figure it out from the picture? OK, here is the trick https://youtu.be/b3vbaZP2cL8 I've include the STL file for those that would like to print one. I would scale it down by about 25 to 50%. The wood version is shown here: https://www.instructables.com/id/Wooden-Illusion/