2 years ago our team looked into alternative materials. Plastics was one. We made a bending table and thermo-formed polycarbonate and polypropylene. We also vacuum formed poly carbonate chain guards. I like this video.
http://www.youtube.com/watch?v=hGBRi...eature=related
This year we made our arm out of fiberglass pultrusions. The methods of working with pultrusions are different than metal. Research and practice are needed for a team to work with pultrusions. We also made our electronics board and some other parts out of composites. Both S2 glass and carbon. Laying up composites is not something that you just decide to do week 2 of build season. Perfect summer research project.