I'm going to have the same problem. I just received an order for a fancy folder with blue mammoth scales.
The only advise I can give is to make a finger hold on the good side using a folded tape. Use your disk sander with 50 grit disk to rough it down. The rougher the grit the less heat is caused. Never dip it in water to cool it.
I added a foot control made for a jig saw to my disk sander so I can stop and start it with my foot. That allows me to get the part against the disk flat, then start the sander. The same holds true for stopping. Let the disk come to a stop before removing the part.
Another advantage is that you can hold the part with both hands and operate the machine with your foot.
