3D Printing

Makerbot sells inexpensive 3D printers that can be used to fabricate parts from ABS plastic.  All of the software and plans are open source.  Gimpy and Prodos were printed using a Cup Cake printer from Makerbot. ROTH and FOBO were made with a Thing-o-matic (TOM) printer from Makerbot.

3D Modeling

A powerful free open source 3D modeling and animation suite that is available for virtually every operating system.  It has a bit of a learning curve, but the payoff is worth digging through the wiki pages.  Blender is ideal for creating models that can be printed with a 3D printer.