WARNING: This product is still in it's prototype stage.
This was a D.I.Y. Project I made a while back for my Raspberry Pi B+. I designed it so that it could be printed from any home plastic printer and assembled with superglue. There are gears that have to be pressed in place and I have not gotten around to actually trying to build it myself. Once you get the two wheels into place, they are meant to be strung together with a piece of tread one can find in an old LEGO Mindstorms Kit. The motors that I meant to use (and are modelled) are: PPN13PB11C sold by Minebea. That should be all, if you do end up finished this project for yourself I would love to know how it went. Enjoy