Inspired by a Khan Academy Engineering blog post, I set out to make make a copy that I could take to the office. http://engineering.khanacademy.org/posts/evil-puzzle.htmThis puzzle has 2 sides, one is decptively harder than the other. Both are the same outside dimensions so they can be glued together.Find out more about this puzzle and how I made it here: ​http://joes3dworkbench.blogspot.com/2015/08/modeling-puzzle-of-evil.htmlhttps://www.youtube.com/watch?v=GPMqMpc3nRM