Skymax 180mm Focus Knob for a better grip (and also a better look !).

Knob has a vent hole to allow full insertion on the rubber knob. Make sure your printer is properly calibrated or it might not fit in place.

I've printed in UV resistant material (ASA).

I recommend printing with the hollow part down on the bed and use support for a cleaner look (due to the chamfer on the knob).