Jim Robinson has built 18 cars using his inexpensive welded steel tube frames.  We will collect details here including how to make his frame jigs, and a step by step guide on how to build one of the most affordable and rugged Electrathon racers.  In the mean time, he has a bunch of info here - http://electrathonoftampabay.org/www/Documents/Jim%20Robinson%27s%20Build%20Process/