About this 3D model
Four parts in all, no support necessary. The spool holding portion is pointed slightly upward to help prevent anything from "walking" (rolling?) off. I used PLA filament for my tests. I printed this spool holder with only 2 shells from a 0.4mm nozzle and 5% linear infill. Pretty skimpy but it held onto 30 lbs. of weight for over an hour without any visible or audible signs of stress.