This is a quick experiment put together in the ModeLab Interactive Parametrics class. You can download the processing sketch in the RAR and play around with it on your own. Hit "s" while running the sketch to save an STL.

EDIT I'm still working on getting a valid manifold on this one. Be warned that it tends to generate files with loads of intersecting internal geometry which will be very unfriendly with your bot.

Save your STL and print. I've included a Gcode file for the Thing-O-Matic for easy printing. If you want to print out the model you generate with this script you'll want to repair it in MeshLab or NetFabb first. The default repair script in NetFabb works like a treat.