This is just a quick redesign on the head of the bolt from this pen adapter by Solstie:
https://www.thingiverse.com/thing:346734
I filled in the center depression and added ridged edges for easier grip. Super easy print, no supports needed. I printed on a raft, because tiny parts makes me nervous, but it's probably not needed.
This thing was made with Tinkercad. Edit it online https://www.tinkercad.com/things/7FlXHqVj41z
Category: 3D PrintingThe author marked this model as their own original creation. Imported from Thingiverse.