The cardboard stock I use is perfect for prototyping parts. It's very stiff and nearly the same thickness as 2mm Stratocore, and it's cheap (well, free with purchase of Bisquick from Costco).

Sad to report that the very fragile prototype LMP body has met its untimely demise. I pulled to the side of the road to make way for a passing car and drove into the couple-inch-deep fermenting algae gunk hiding against the curb around the corner. The primordial ooze dissolved the paper bodywork and cardboard prototype underfloor system; a total loss.

The Traxxas runs really well with the light kit and an aero kit on. It's very fast and very stable and a good time, even in the dark.