This is the knob for M3 CAP bolt. I made it so that the fixing screw of the fan nozzle shroud of Prusa i3 MK3S can be turned by hand. It is convenient because the shroud can be removed immediately when cleaning the nozzle or replacing the nozzle. Of course, it can be used for other purposes as well.

Use long M3 CAP bolt and M3 hex spacer(long nut).
-M3 CAP bolt: original bolt length + 15mm (=35mm in case of fan nozzle shroud)
-M3 hex spacer: about the same diameter as the CAP bolt. The length is 10 mm.
.
The hole for the hex spacer is designed tightly, so pull in the spacer with bolt.

Prusa

I3 MK3S

Doesn't Matter

No

0.2mm

15%

brim: yes