NXT LEGO roller ball

This is a third wheel for any two wheel powered robot. Print this with supports for the top piece. Bottom piece needs to be trimmed off from the bottom of the ball. Works as a fidget spinner as well. Scales.

NXT_Roller_CH_V6.stl comes with a cut away base support for the ball. If the cut away fuses to the ball too much, lower your extrusion. This still requires supports for the rim.

I've included stl file without the base cut away in case you want to print the the roller ball and rim with your own supports entirely.