Some time back I printed off the Heavy Duty filament spool (http://www.thingiverse.com/thing:11447) and love it. It keeps my filament out of the way mounted to my printer. However my recent batches of filament are coming on spools already but I don't want to mess with any other form of filament system. The solution was a hub that is compatible with the mount (http://www.thingiverse.com/thing:10254) of the filament spool system but is designed to hold the new spools. Spool has a center hole 76mm in diameter but is too thick for the mount. The solution was to print a pair of these hubs, one for each side of the spool, with bolts holding them in place through the center of the spool. My printer is currently down for further upgrades so have not had the chance to get this printed to test it out.