Angle grinder belt sander. By KS Mechanical Engineering. 16:29 video:
https://www.youtube.com/watch?v=LIDDX2Rjxw8
Previously:
Getting More From Your Angle Grinder by Tuomas
25 Plans for Homemade Belt Grinders
Multifunctional Belt Sander/Grinder by meanwhileinthegarage
63 Best Angle Grinder Hacks
Lathe Belt Sander by AB-SHOP
Angle Grinder Pipe Sander Attachment by Tuomas