This a new version of my universal spool holder http://www.thingiverse.com/thing:378776
This spool holder is using 4 standard 608zz roller/skate ball bearings to limit friction. This new version is larger by default and clips onto the beam to be a lot more stable.
Print two sides and optionally two rollers. The rollers adds stability to the spool. Print them if you are not using a rigid spool or if the flanges of your spool are not exactly parallel.To print the side parts it could useful to add a brim with FDM otherwise the clips may not stick well to the print bed.
Insert the bearings onto the pegs. They are designed to hold them firmly. If you want to limit the friction to a minimum the best is to use dry ball bearings (remove the covers and dissolve the grease in acetone or d-limonene). In theory your spool holder is ready but if you plan on using it without the plastic rollers make sure the flanges of your spool are exactly parallel (they often are not !) otherwise you will risk a drop and to brake anything fragile beneath. Clip the support sides onto the beam and space them so that the flanges will lie onto the bearings. You can put any spool size on it, you are just limited by the size of the frame.