Universal spool holder with two ball bearings. It can fit any spool size, width is adjustable. "Fast change!" between spools, little friction while it spins. It is componed of: That's it. You need something to hold the 8mm bar in it's horizontal position while the spool spins. I used two 8mm threaded bars as pillars with two "vertical_support.stl" on top of them, but you can use anything you want. The less the spool opposes force while it spins, the better is for the printer. An easy to move spool can make a difference on your printed parts Video: http://www.youtube.com/watch?v=-YkU3YFIYhw