Over the years I've bought sanding mops from various places. My favorite is Klingspor's Woodworking shop. Nice info and video here:
However, when I don't have time to wait, or I need a specific grit, I make my own cut sandpaper. Normally, I cut 2" x 6" cloth pieces. Takes about 25 minutes to make and mount 48 sheets. Normal cost would be around $30 + shipping.
I made a simple template from some scrap phenolic sheet I had. Marked and cut the slots and drilled a hole for the center.
I get 8 pieces from a 9 x 12 sheet.Slit the cloth. I have a bunch of slightly used blades from cutting covering material (I change blades often when cutting covering material). I get about 8 pieces before I toss the blade. You can also make a couple passes on a diamond hone, but blades are pretty cheap, so I don't do that much anymore.
I also use 2" roll cloth. This goes a bit faster.
The Mandrel can be as simple as a bolt, couple of washers and a nut.
Alternate face up face down with a half overlap.
You can use on a drill...
or a drill press.
I often use several different grits on my long mandrel.
I use the sheet scrap on my Dremel.
I also have a simple sander/buffer made from worn out hook and loop discs. (I don't like throwing much of anything away).
I cut a round template from phenolic (you can use plastic, wood or whatever you have around for templates)
I also mount these face up face down.
I use this without buffing compound mostly for fine finish on wood, and a regular buffing wheel with compound when doing metal.