Big thanks to Tom Klein for a great modification of SoM’s filament spool holder!
The original design used to have a printed ABS top roller and I just pushed the roller against the flanges and finger-tightened the nut. The problem was people kept taking it apart, so I added rubber bands to pull the roller down, and a nylock nut to prevent tool-free disassembly. Then the rubber bands kept disappearing, and Tom came up with the idea of making a heavy top roller so the rubber bands wouldn’t be needed. He cut a new, steel top roller on the lathe and it works great! The bolt is just loose enough to let the roller slide up and down in the slot in the frame. The roller is heavy enough that it just falls into position on the spool flanges.