3D printable snap-together tank.
Tracks Chain and Pinions is, of course, a derivative of the masterful Chain and Pinions by aubenc (http://www.thingiverse.com/thing:5656).
The drive shaft is also a derivative of Large Threaded Bolt and Nut by ub3rgeek (http://www.thingiverse.com/thing:4880).
Many of the parts are also derivative of my 9 Volt Racer design (http://www.thingiverse.com/thing:4818).
Still wishing for a multiple derivative feature on thingiverse!!!
I like to print successfully before uploading, but this design's been sitting on my desktop unchanged for several weeks. It is designed to work with a pair of 600 RPM DC motors, which I do not have and since I've blown my R&D budget for the next few months, I doubt I'll finish it in the near future. Any help completing this design would be greatly appreciated!!!
UPDATE: I did eventually obtain the motors I needed, but by then I had designed version two of the tank - http://www.thingiverse.com/thing:8080
Detailed instructions may follow if I ever finish building mine!
NOTE: The STL file is completely useless for 3D printing-- I only uploaded it for the nice thumbnail image. The parts (including right-sized treads) are individually laid out in layer 2 of the blend file.