I use cd box for the wheel.
for the chassis, i bought a cutting board at ikea (the plastic is easy to cut and drill and strong enough)
The only thing i build with my hand is the servo mounting bracket.
And it was not so easy : I used a very old PC to find my material ; I cut into some aluminium parts and drill 3 holes
So it takes me an afternoon to make 6 usable the servo mounting bracket. ;-)
look at this one :
the next steps to do :
- find a caster - use the SRF05 I bought solder the row PCB Header Plug on it to plug find the way i mount it on a servo
- create the code ; so my robot really will be autonomous
Here's a caster that looks pretty good. And it's way cheap.