Parametric Robot Wheel (Circles)

NOTE: This has been upgraded to a much more flexible version that incorporates all previous designs and adds lots of new features.

The new version is here: http://www.thingiverse.com/thing:21486

This is a flexible parametric robot wheel with a "circles" pattern. It's a variation of the biohazard wheel code here thingiverse.com/thing:21010 -- but it's tweaked a bit to support the circles design specifically.

There's a slot for a captive nut and hole for a set screw that are a little di