This squashes into the side of one of Makerbot's filament reels so you can attach a power drill to re-wind filament perhaps from reels that don't fit on the back of the machine properly.Print it with a 30% fill to keep it reasonably strong and fit a 8mm bolt through the hole. Lock the bolt on with a Nyloc nut to stop it unscrewing in use (or use two nuts).Remember to spin the drill slowly - you wouldn't want the reel to fly off and decapitate the cat, now would you?