Very minimalistic stackable spool holder, only 3 different parts. Actually axle must be printed 4 times per spool, body part - 2 times per spool, spacer is for 58 mm spool width. For other spool width you'll need shorter / longer spacer, I don't have any with different sizes so you'll need to modify spacer yourself. DS Mechanical file attached, feel free to alter it to meet your needs. And you'll need 4 608ZZ skate bearings too...

Update: added POV-Ray renders.