Vilko's Filament Spool Roller - This is an assembly that combines both 3D printed parts and standard hardware into a robust spool roller that can be connected into a series, if desired.  I designed these to be simple to assemble but sturdy regardless of whether they are printed in PLA or PETG.  I use these in my dry boxes with 4mm ports, allowing the filament to easily feed from the box into my printer. This will accommodate up to 75mm wide spools.

The assembly consists of the following parts:
3D Printed Pieces (1 of each half, 2 axles, 4 items total)
(2) M8 X 100mm threaded rods (100mm min. length, can be longer if desired)
(2) M8 hex nuts
(2) M8 fender nuts
(4) M8 washers
(4) 608 bearings (22mm OD x 8mm ID x 7mm thk)
(4) #6-32 x 1-½" screws w/ nuts (optional for connecting multiple assemblies together)

I printed these beefier than they probably need to be, using 4 walls and 5 layers (1mm) top and bottom walls, along with 25% infill.  Supports aren't required for the two halves, but -will- be required for the axle part. None of the holes require threads/tapping while the bearings and the hex nuts are press-fit.