A 3D printable replacement pin with pull ring for fire extinguishers. I tried it on 3 different model extinguishers and it fit all of them, so it might be kinda universal.

The pin is about an inch long, and about ⅛ of an inch across:

I recommend printing it in PETG or ABS, as PLA might melt or soften in storage of the fire extinguisher or in a situation requiring its use.

I should clarify that this is a replacement for a pin that is lost or broken, but is not intended to allow a fire extinguisher back into service after it has been used. Even if only partially discharged, a used fire extinguisher should be replaced.