This is a small ball caster to be used on robots or other things that need to roll.

The openscad file is set up to easily tweak values for commonly changed parameters:

Ball Diameter Airgap - How much play between the ball and the wall Ball protrusion - How much the ball should stick out of the housing. Total Height. Base thickness.
Mounting screw radius. Spread between the mounting screws.

I've started playing with a parameter to switch between two different mounting types. This isn't done yet which is why the part is marked as a work-in-progress.

Ears will create a part as shown in the picture. Meant to be mounted with two external screws.

Center Screw would have a counter sunk screw in the center of the main cylinder. The caster could then be screwed in before the ball is snapped into place.

My reprap isn't particularly well tuned but the ball spins freely.

I'm incorporating this design directly into scout. http://www.thingiverse.com/thing:13042