You may wanna look at these:
(the pic is big so i'll just put a link)
http://jamesyong.net/rubbish/track/b...0assembled.JPG
more track photos here:
http://jamesyong.net/rubbish/track/
basically an approx 40x40cm bot, the first "large" bot I made back in 2004 weighing no more than 10kg. Tracks came from a kit. Hope you can get some ideas out of there.
