I wanted a spool holder that clip on the spool and use as less space as possible because I will put my spools on a threaded rod over the printer in my rack-mount, so I can put 5 spools in one bar! Also this spool holder use a standard ball bearing, so it turn very smoothly. The STL file work with a standard skateboard ball bearing (22mm x 7mm), inside spool diameter of 56.5mm and tickness of 6mm. SCAD file is included so you can set your spool size, see instruction. UPDATED 2014-12-17: With the suggestion of sgraber, I added 2 new variables to remove the locking ring and disable the hole to save PLA. Also now the hole to save PLA will work with smaller diameter of any size. UPDATED 2014-12-19: Youtube video added: https://www.youtube.com/watch?v=p5wZdxiFyGA UPDATED 2014-12-20: Updated SCAD script, I changed some variable name (bug from find & replace) and corrected a bug with the spool tickness. Also I added a new STL with different dimension, I use both of this configuration. UPDATED 2014-12-21: New youTube video added with more spools https://www.youtube.com/watch?v=lng9eZjR9RE&list=UUg0rSjryYrw6MFuhJREnz4w UPDATED 2015-01-03: Updated SCAD to support better bigger ball bearing size and bigger spool diameterThe only thing you need to set is the spool_inside_diameter and spool_tickness so that your spool holder fit correctly on your spool. Once set, save and build the model, once build, export the STL file on your printer. Print the spool holder without support material.