My next project is making my own rotary tool out of an electric hand mixer. Even just the aluminum fan in the mixer cuts deep into wood and plastic with no problem, and has a 5 speed switch built in. The fan in the mixer is connected directly to the motor, on a worm gear shaft that turns the gears that spin the beaters. If I attach a circular blade on the shaft the fan is on, it would spin about 15-20 times faster than the beaters would.