FLEXTRAK ALTERNATIVES - DIY flexible dolly track
 

Well, I don't know what happened to the alternative flextrak alternatives, but I'm actually looking into some hydraulic hosing that although it isn't solid, it just might be heavy duty enough to handle the weight distributed across 16 wheels, and at 2.28 a foot would be an extremely reasonable cost. If not for supporting a human and camera, it might be fine for a tripos system:

http://cgi.ebay.com/ws/eBayISAPI.dll...516765900&rd=1

or, for flat surfaces, there is the solid half-round stuff (also at http://www.acmerubber.com/round.htm as was mentioned for the 'cord' material), again, it might be sufficiently durable (not sure if it can be durometer/shore rated [as if I know how that translates to dolly requirements!]), but if it's solid enough it would be great for a flat surface!