Today we printed and assembled the two types of decasphericon models from chriskpalmer's Sphericons on Thingiverse. We used Gorilla Glue to install 3mm Neodymium Rare Earth Super Magnets in the holes of the model and are impatiently waiting until tomorrow to be able to snap the two pieces together and roll the thing around!
Thingiverse link: http://www.thingiverse.com/make:52970
Settings: Two halves at original size with Makerware .3mm/low, in 3 hours and 10 minutes.
Technical notes: The Gorilla Glue seems to melt the PLA a little bit, but so far only to the extent that the tweezers we were using had some red on them after using them to insert the magnets into the glue.
Fun travel fact: You can play with lots of models like this in the Twist 'n' Roll exhibit on "Floor -1" of MoMath, the National Museum of Mathematics, in New York City.
UPDATE: On the first try, the magnets did not work very well for me. Two reasons: First, I think I put too much Gorilla Glue over the magnets and this decreased their power. Second, of course I didn't pay any attention to the directions of the magnets and this makes the halves only stick together weakly, and only in certain rotational positions. :(