Tesla Model S/X lug nut cap puller, designed for 21mm lug nut caps. It should also function for other vehicle caps with sizes ranging from 20mm to 22mm, and its size can even be reduced to serve as a mechanical keyboard cap puller. (No, I don’t know exactly how much to reduce it—just experiment with it.)

Features:

Self-retaining tension on caps
Shirt clip
Easy to hold
Bulk printing – I’ve printed up to 4 at once with no problems.