I very much liked Electronic Wire Spool AWG Wire Spool so I've designed and printed gridfinity storage for it.

I've used the standard printing profile as well as 200% scaled version for spools, so I've designed two versions of organizers.

The small one is 4x2 gridfinity slots and holds 7 spools. The big one is 4x3 and holds three big spools with about 2 centimeters left of free space.