I make some wheel hub adapters for an FRC team I'm a member (and mentor) of, FRC team 4802 - Unidentified Moving Machines (UMM).
These hub adapters are to mate some 125mm (6in) omni wheels to some 42T timing pulleys that have mismatched PCD patterns. Wheels are from RotaCaster (an Australian company), and the pulleys come in the standard kit of parts (KOP) box from AndyMark in the US.
If you haven't checked out this year's robot challenge, watch this one instead: https://www.youtube.com/watch?v=EMiNmJW7enI
The metal came from http://www.aluminiumonline.com.au - very happy with their service. Check them out if you're in Australia!
NOTE: since filming, I've parted about 4 more discs this size, and it's improved. A bandsaw / power hacksaw would be nice!
