i do it all the time, i use junk cd disks frequently. just about any disk with a proper hole in the center can be used. experiment, be brave. you wont hurt anything if a backing is needed, try a disk of .125" plexiglass-- commonly used to make windows for storm doors & such.
Probably 82 I bought a power hone from GRS. Thought about a blank at that time. Got a 250, 600 and 1200. The ceramic was I think $89 at that time so used a 1 inch by 4 inch white ceramic stone set on my power hone, don't use power with the ceramic much anyway-works great, put a refrigerator magnet on one side to keep from vibrating off the hone when not in use. Just slide it under the turning disk and that where it stays until needed. Said to self " when you ware one of these 3 grits out you can use it as a backing lap for alternative diamond disks. Never wore one out. Work dry, Give them a good scrubbing with Dawn and a hand brush once in a while. Bought the blank about 6 months ago to make a power strop when I was thinking about trying my hand at bright cut. Have tried a tip the Monkster shared about rolling diamond dust into cd to polish with. Fred