I really liked the hanger design by inagakitakahiro, so I remixed it to four different variants that can either hold 6, 8, or 10 belts. A thicker design is used to support added belt weight.
I imagine it can hang other things as well, e.g. necklaces, ties, etc..
I recommend 100% infill. PLA should be strong enough for average belts.
Want a smaller travel size version, check out
https://www.printables.com/model/1444485-travel-double-quadruple-hook-belt-hanger
The author remixed this model.
Remixed to hold a different number of belts, adjusted size, length and made thicker to be stronger.