MityVac Valve cap screw for fluid evacuator.

thingiverse

I printed this upside down with the mushroom top on build plate. This will allow you to limit supports needed to print. I used the threads on the shaft assembly to screw directly into the shaft of cap screw. Just have to be careful. You will probably want to use a high infill. I think I used 60% as the first one I made was too weak and broke when I was screwing on shaft. I hope this helps. Funny enough this was my first ever print and design.