George Hart has a lot of great models over at his MakerBot page: http://www.georgehart.com/rp/makerbot/makerbot.htmlHe's given me his blessing to post these to Thingiverse where they can get some additional exposure!This subgroup of parts is the printable math structures-- I'll be posting the more puzzle-like ones in a separate post. He reports these can require a lot of cleaning, but otherwise come out pretty nicely!