VoilÃ , here is the my version of a dispenser for filament spools made from printed brackets and wheels, together with some leftover M8 threaded rods and a couple of 608 bearings, and a toothbrush to stop the rotation softly.
This design is easily adaptable to different size spools (as long as the centre hole is 51...59mm).
The picture of the assembled dispenser shows that the wheel does almost slip inside the spool, so I changed the outer diameter in order to avoid that issue. The wheel has now a small diameter of 50mm, and the outer diameter is now 60mm.
I added another picture showing a "lightweight version" for a BFB filament spool. When I received and assembled the RapMan kit, I was not so impressed by the original laser cut design BFB provides as it it quite wobbly. I modified it using my bracket+rod design and kept the 2 acrylic discs as the inner diameter is >60mm. However, I made sure the discs do have clearance to rotate smoothly (spares you the need for bearings). Again, I used a toothbrush to stop the spool from rotating too much.
You gonna need to print 12 brackets and 2 wheels, 2 off 608 bearings, a bunch of M8 nuts and washers, 3 wing nuts (M8), and 9 pieces of leftover M8 threaded rod (150..200mm each, depending on both the bracket angle and spool dimensions - you better double check with you filament spool). The toothbrush (medium/soft) is fixed using cable ties and just touches the spool between the ribs.
One screen shot shows a cross section of the centre axis assembly. The wheels are actually cones, so they will press against the spool once you tighten the whole thing up, so there is no need for any other nuts inbetween both wheels (this will just cause friction as it will work against the bearing layout).
The number of washers between the wheels and the brackets can vary as you need to check the distance necessary for placing the toothbrush. On my prototype, I used a M8 nut instead of a set of washers. However, I will swap the nut for some washers in order to make things easier for future spool replacement. The idea is, that you undo the 3 wing nuts to lift off the whole front frame including the toothbrush, then replace the spool with a new one, and join the frame back again.
I will see how this is going to work - I have not tried this "easy-swap" functionality yet.