Sean: The wheels are more for the cool factor, and it's something I've been trying to do for about a year now. The rollers have a solid plastic core(abs) and neoprene heat shrink for grip.
Kres: I am going to get them done, and I WILL rub it in your face...
Budda: Yea, collars aren't cheap...
I've checked places like McMaster, but Vexlabs still is the best price. Any ideas for alternatives to shaft collars?
Tytus: Thanks. I was inspired mainly by your designs and wanted to bring the mecanum to vex.