These dividers only fit over the default rail size. They fit snugly onto the rail and can be glued down to sit tightly in the drawer.

I didn't want 12 separate drawers, so I printed 6 and made these dividers instead.

Print upright with supports for the overhang. PLA works fine, PETG can give a bit more strength.

Currently works for spools with a 63mm ID, 220mm OD and 54mm Height, but I've included a step file for easy modification.