Tire Valve Cap, a bit smaller for you to twist and adjust better.

thingiverse

I made the cap flat, without the logo, first. The cap was loose and a bit too big. So I narrowed its diameter from 10.5 mm down to 10 mm. It fit perfectly after that, but if you screw it in all the way, air comes out because the cap touches the needle valve. Finally, I added a dome so the cap wouldn't touch the needle at all.