This will cradle a reel type filament spool allowing smooth unreeling while printing. This will hold the small spools that T-Glase comes on all the way up to the large spools most filament comes on. NOTE: This is marked as a work in progress as the bearings I used came preassembled with the grooved spindle from Vetco.net. This design is fully functional but requires these grooved spindles. They are the primary design feature that makes these functional. I have included a piece that is the spindle that will fit a standard 608 bearing. This will require the following, but may vary depending on the bearings you use... (2) printed base parts, they are symmetrical (4) bearings 608, (mine came from Vetco.net with spindle) (4) printed spindles, (if your bearings did not come with them already) (4) bolts, M8 40mm (4) lock nuts, M8 (8) flat washers, M8 If you printed the bearing spindle, then you will need to press the bearing into the spindle from the beveled side until it is centered, which should be all the way against the inner race of opening. Make sure to assemble with the flat washers sandwiching the bearing. Tighten so the bearing doesn't rock and rotates freely. The spool sides rest into the groves of the bearing spindles.