If you're looking for an insane paper related challenge then check this out. I found these (and a TON more) amazing paper toy printables on the Canon Creative Park website. The selection of printable toys on their site is impressive. I've been too intimidated to try any of the moving toys, but I reeeeally want to.
Did you know that toys like this originated from Japan? It makes sense, since, you know, origami and stuff. There are still competitions in Japan to see who can create the most elaborate paper trick box or moving toy. I think it sounds fascinating.
So if you happen to find yourself with a lot of free time, ink, and paper, pick your favorite paper toy from Canon Creative Park and then let me know how it goes!