I am sanding the shoulders of the Sounder, and the yellow pine is second growth, somewhat softer than old growth. The difference between spring wood and summer wood is pronounced, and using a sanding mop produces a Shou-sugi-ban finish. I wanted a full-width flap.
I made 3 – 4″ octagons 2″ thick. I had a 2″ polishing head that would mount in the drill press. Using a 1/16″ blade, I cut 16 slots in the faces of the octagon. Using hot glue, I glued in 16 2″ x 4″ flaps of 120 grit sanding belt. I also ran a bead of glue just behind the flap.
Works like a charm. Wear gloves.
This is what happens if you use staples. Now you see why I made three octagons. The last one uses 240 grit paper.
Update: the latest version has 32 flaps. I made an octagonal column, and cut nine two inch thick octagons.