Control knob for 6mm diameter shaft

I'm building some electronic gadgets and I needed some knobs. I didn't like any of the knobs that I found so I designed my own.

Comes in versions with and without a direction marker on the surface; for extra fun, if you have dualstrusion you can also fill in the mark with a different color. (I haven't had any luck with that on my Replicator Dual but maybe someone else will have a better result.)