A solution for refilling Zim filament spools. Zim uses a proprietary filament cartridge system. Popping open the case reveals the filament spool. Squeezing the sides of this spool allows the top to be removed. These sprockets can be attached to either side, with the hex shaft going to a drill, and the other held in the free hand. Insert the new filament in the hole at the base of the spool and rewind the spool. Be sure not to lose the little black o-ring that fits in the groove in the neck of the cartridge.