HDD Grinder Mod - Turn your useless HDD into a powertool
 

After re-arranging the disks, the next step is to cut the sand paper. You can use ready ones if they happen to come in right sizes but I decided to cut one of my own. Just a piece of P100 grit paper, a sharp blade and a disk to be used as a template. A bit smoother paper (P600 and up) could possibly eliminate the torgue-problems the tiny motor sometimes has.