This is a simple grip/holder for regular 5" circular sandpaper pads. Just apply two strips of the hook part of Velcro (or similar), and optional some strips on the sides, and you are good to go.

I printed it in Overture PLA+ with 0.2mm layer height.

The photos are made after using it for a few weeks of renovations. I've used it for both drywall/paint and wood sanding.