Stovens - EMT is electrical conduit. It's galvanized (zinc dipped) steel. Very thin wall and pretty light. I am using aluminum in a few places, but the main part of the frame is conduit.

Bob - That Eliici is interesting... If you're serious, you can get all the stuff you need from EV Parts, Pentad Motors, Cloud Electric, and others. There's a list of resources on the Electrathon website (www.electrathonamerica.org).