has anyone else ever tried:
taking the barrel (after gluing the halves together & letting it dry)
and wrapping a small square of sandpaper completely around the barrel,
then twisting the barrel inside the sandpaper 'sleeve' ?
Yep, I have tried it. It is a great technique.
I forgot to mention that, you can pick these sponges up and any department store, usually in the paint-thinner-tape section. I have the fine and extra fine grades.
They also work well on larger, flat parts. I lay the sponge on the table and run the part over the grit. This way, the edges get sanded in uniform fashion.