I tried other "spool holders", but they all hang-up or bind sooner or later. Other "rollers" require filament guides and occupy work surface space. I wanted a spool holder that was out of the way, didn't clutter up my work space and provided smooth distribution of filament preferably with bearings that I could change out when needed for a variety of spool sizes. When I used other "holders", often I would have to tighten my filament feeder bearing so tight it would smash and oblong the filament so it wouldn't fit through the extruder and would jam up. This ruins a lot of filament quickly. Other "rollers" need guides to get the filament up and over everything to get the filament from the spool to the extruder because they sit on the work surface. Each of these "guides" can also jam up the filament or require bearings themself. It seemed that it could all be done easier...... I give you the Tri-Adapter Axle. I started by measuring the inside diameter of the spools that I had. I came up with 4 common sizes, all included in my design. I haven't found a spool (yet) that doesn't work. I used a 3D printed angle bracket for PVC that I made and some PVC fittings to mount it above my printer. With 3/8" ID bore bearings: https://www.thebigbearingstore.com/r6-2rs-r6-zz-radial-ball-bearing-3-8-bore/ that pop into the Tri-Adapter body, the whole thing easily screws into a 3/8" coupling nut I mounted in an adapter I also printed that presses into the PVC fittings, all freely spinning on a common 3/8" bolt as an axle. I ended up getting two different length bolts for different width spools, but one long bolt could work for all spools. I hope it serves you well - ENJOY!