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.
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.