I got hooked on the Thingmaker app and made a Raptor. I really liked the designs and searched through all the ones listed here when I found the wheel.

My design was inspired by Marakew's wheel: http://www.thingiverse.com/thing:491232

I knew the design was faulty, but it got me thinking about how to make a functional wheel for the Modio/Thingmaker parts. It is essentially it's own bearing, with two parts printed together. I added tiny supports across the center piece to the exterior to prevent the parts from being pulled off the print bed. They just need to be cut or broken to free the wheel.