Stack some hats against a wall to make room in your closet.
Found some similar models but nothing that fitted my needs, so made a quick design in fusion and tested it out. works for a lot of hats, but as you can see on the image, it looks messy after 6-8.

I printed it with PETG, and 3 walls, wich makes it solid without infill as long as you use a .4 nozzle.