I got tired of the multiple, awkward spool holders that have poor angles and friction which frequently "slip" and make noise (leading me to come check on my print every 3 min). I designed this multi-spool holder in blender that is thin enough to support all standard spools, and those spools now float [almost] frictionlessly behind the printer. It's also 100% printable!
NOTE: You must print these together! (that's why the only files I submitted have both parts). Otherwise the long rods that print at the end print too fast and deform because each new layer starts printing while the previous couple layers are still warm and deformable. I explicitly laid them out the way they are so that the print head has to travel back and forth while printing, giving the layers time time cool in between.
I think I will update this design in the future to have the bar be a separate object that snaps into the two holders.
UPDATE: I designed this originally to attach it to my printer, but I didn't realize that it works standing up too! So it's not really specific to to Rep2/Cube2, unless you want it attached.