I modeled this to look like an actual pill capsule, but I wanted something that had threads that were easy to start and didn't take a lot of turns to secure. I printed this one in blue silk and white PLA at .24 LH with a .5 nozzle. Kinda chunky, but it works. Printed both thread-side down, the male side with an inner brim and the female with an outer brim. If you get an error that there is ‘an object with no extrusions on the first layer’ (PrusaSlicer) then simply cut the bottom (non-dome side) .2 mm off and re-slice. The model comes to a sharp point and seems to play hell with my nozzle/printer settings.