I buy mine from a local place - theplasticstore.com/
For you Canadian Toronto-area guys, they sell Delrin in just about any size you want, for reasonable prices…
Shipping is pricey, but you can pick it up for free.
- Jon
I have used 1/4" and 1/8" with good results in plexi.
The 1/8" hopefully will hold up fine for me, atleast for a bit. I just wish I could find time to work on this with school! 
I feel your pain, lets lobby for 4 day weekends.
…does that count for wheeled / non-TRACKED vehicles too? In the same situation i mean…Like if JRDRAG’s motor units were running wheels instead of tracks…
…Man i HATE being a noob again 
While at Ikea today with my mom, I saw some drawer dividers that I could not pass up getting. They will be used for my main chassis. I’m going to create a box using them. Though the thickness of the aluminum is very thin, I cannot flex the pieces with my hands. Not bad for $12, I got a couple of pieces. Camera phone pics again 
http://i172.photobucket.com/albums/w6/jbflix/0121081744.jpg
http://i172.photobucket.com/albums/w6/jbflix/0121081744a.jpg
Yes this applies to any differentially steered vehicle. The wider the base the easier it will turn.
Those are some nice extrusions. Light yet strong. Good find.