There is now a new version of this holder, with a filament guide:
This is the remix of TUSH - The Ultimate Spool Holder. One major improvement is the foot added for extra stability - I found the original holder to tip over too easily. I also chamfered the cylinders slightly, to make it easier to put the bearings on. Still only one part to print, 4 times.
To assemble, just put the bearings onto the pins and press two parts together. If the fit is too loose and you want to glue them together, the convenient place to put the glue on is the cutout for the foot of the other half of the holder, the tolerances should be tight enough that the foot touches the other part.
I printed it in ABS, but PLA should work too. I recommend changing layer settings to 4 shells at 0.2mm, so you don't get any infill in the thin parts printed vertically (they are horizontal parts in the final object). At different resolution, you may need a different number of shells. I found that drawing squiggles for infill in the tiny gap between shells just slows down the print.