I just finished this sanding disk organizer for 2" and 3" disks using plywood, 2" & 3" PVC pipe and a lazy susan base.
When I cut the open slot on the pipe segments, the pipe diameter closed slightly so I cut 2" and 3" circles from 1/4" ply and glued them to the pipe segments to maintain the correct diameters. A word of warning: Use a dust collector and wear a good quality dust mask when you're cutting/sanding PVC. It produces very fine particles of dust that you do not want to breathe in.
I purchased a set of KJR quick-release backing pads & a holder for my 2" disks two years ago and they have held up very well, so I recently bought a set for 3" disks as well.