I used the max print quality that I could (0.12mm per layer) but it would work with much less detail than that. With that level of detail it took about an hour and 15 minutes per hanger but that time could be taken way down if you used less detail.

The screws I used to mount it were just some cheap ones I got from Princess Auto. I don't remember the brand they were or the exact size but the holes for the screws are 4.5mm for the small hole and 8.5mm for the large hole so make sure they fit that specification.

This design should work for both fitted and adjustable hats. It did for me at least.