LH, see my earliest post in this thread. You get a dimmer switch -- but it has to be one rated to use with electric motors (go to a real hardware store and ask the lighting person). Most dimmer switches are resistor-based, and will destroy motors. But some are designed especially for use with motors (e.g. ceiling fans) and that's the kind you want.

Wire it up with a 39-cent power outlet, a cover plate, a cheap box (scrap wood will do) and a power supply cord (get a cheap outdoor-rated extension cord and cut off one end). (Wiring diagram available upon request for the electron-challenged.) Viola! Variable-speed Dremel.

Alex