Homemade forearm shredder. Basically you roll the PVC pipe until the rotor rises to meet it, put it down and unravel, then switch sides and roll it the opposite way to work the other side of your arm. It works really well.
Basically all you need is a PVC pipe approximately 3 feet in length, some rope, and a weight - in this case, my old rotor. Drill a hole in the middle of the PVC pipe, thread the rope through and tie a strong knot. Tie the other side to the brake rotor, and boom, you're done.
I start with the rope already wrapped around the pipe several times, so the weight isn't solely on my knot.