Some of the nice things about this spool holder are: * It goes on the top of a full-sized Kossel printer (which uses 360mm horizontal extrusions), so it doesn't take any desk space, and it allows suspending the extruder below it, so that you can have the shorted Bowden tube possible. * It works with almost any spool. * Because the spool is spinning on bearings, there is very little friction, so the motion is especially smooth. Print one copy of the copperSpoolHolder.stl -- which contains two parts, one for the left side and the other for the right. Print two copies of copperPipeBearings.stl -- one for the left, and the other for the right. You'll need the following: * 4 623ZZ flanged bearings * 6 M3x10 screws * 6 M3 nuts * 1 ~230mm long piece of 1/2" copper pipe. Use four M3x10 screws and M3 nuts to attach the four 623ZZ flanged bearings to the copperPipeBearings parts. Use two M3x10 screws and M3 nuts to attach the copperSpoolHolder parts to the left and right sides of the top horizontal extrusions of your printer, the right distance apart so that the 1/2" copper pipe can rest in them.