I can tell you what not to do with one.
I once had the idea of using a vacuum cleaner motor to drive a flexible shaft and hand piece tool for small grinding and drilling jobs. I built a sturdy set of gimbals and attached them to the motor so that the motor driven shaft was pendulous. Screwed the gimbal set to the ceiling in my shop with three long stout screws, well secured into the beam above. Connected the wires by simply twisting them together for a trial run. Intended to tidy them up later and insulate etc. Connected flexible shaft to motor and was ready to go. Vacuum cleaners where I live are all 230 Volts AC. I held the hand piece and turned the power "ON".
The torque was so high that it tore the motor, complete with now mangled gimbals, from the ceiling and whilst still going wrapped itself around my head and shoulders. Small exposed fan blades screwed themselves into my tee shirt and left nipple, lots of pain, and live wires gave me several bad electric shocks. It all happened in a couple of seconds and luckily my reaction in falling over ripped the plug from the wall socket and it was all over. Never again. I decided that the speed and torque were way to high to drive a flexible shaft tool.
Sorry I can't be of more help. I also hate to see good things wasted.