Removable filament roller slides onto on a 1x board.
This was inspired by the 3D Printing Nerd Filament contest and built to solve a problem I was having the amount of desktop space a Prusa with MMU required (details at the end if interested).
Filament should unwind toward the back of the wall to be properly supported by bracket. Roller will roll freely in the holder as long as you leave a little bit of space and don't have the end caps up against the brackets. Roller should be able to slide left and right a little bit and then it will roll freely as well. Roller is a separate piece that can be adjusted to any length desired by scaling z height when printing. It is sized to fit the widest filament roll I had without adjustment. Roller is 3/4 inch wide so any other 3/4 inch round material can also used.
Two endcaps are glued onto each roller. The endcaps have holes for loose filament if you are not using the bowden tubing solution.
There is also a bowden tube guide/holder. This is optional but recommended to capture the filament. The 4.2mm hole worked perfectly for me but I included a 4.3mm version as well.
The intended set up for these is to glue the bowden tube holder to the front as shown in the pictures. Feed about 4-5 inches of tubing up from the bottom to capture filament coming off the spool. Bowden tubing exiting the bottom can simply be a few inches long to prevent to filament from loosening up on the spool and tangling or it can reach down to the printer.
If you run the bowden tub down to the printer and leave some slack then you can feed the printer at any angle you need. In my case I ran 3-4 feet of tubing out the bottom. I used enough tubing to make a loose J formation into the inputs of a Prusa MMU. The extra bowden tubing allows the MMU to feed from the downward direction off the spool into its 30 degree upward feeds without the filament having to make a sharp turn that would break the filament.
You do not need expensive bowden tubing for this since you are just using it as a pipe to control the filament - cheap 4" OD 2" ID tubing is fine.