Knobs with bits on...

[MG01]

Does anyone have any suggestions where one might get hold of something similar to this star knob but with either a nylon or leather none marring tip?  It's to replace the focus lock on my William Optics 66SD as the thumb screw is a little dificult to tighten with cold or gloved hands.

https://www.zoro.co.uk/shop/standard-parts-and-machine-elements/star-knobs/gn6336-4-st-25-m5-20-star-knob%3B-polyamid%3B-bolt/p/ZT1072122X

M5 25-35mm length with Nylon tip?  Alternatively I guess I could just epoxy a leather pad to the end?  although I'm not sure how well that would work...maybe if I grind it flat first?

thanks

[Carbon Brush]

An idea?

Put a couple of nuts on the M5 shaft, then clamp it into a vice.
Drill a hole in the shaft and tap M2.5 or maybe M3.
Fit a short M2.5/M3 nylon screw into the hole.
The M5 knobs are cheap and on sale with MOQ 5 so it doesn't matter too much if you wreck one (or two).

An alternative is to buy an M5 nylon bolt.
3D print a knob style cover for the head - probably as two halves glued together.

HTH, David.