I'm attempting to construct my own disco style party light, the type that DJs use at parties. I plan to have 3-4 different colored lights that will flash on and off rapidly. I considered using LEDs but incandescent light bulbs seem to be a cheaper, more practical alternative. I will control the flashing using and Arduino board somehow (this is my first experience with Arduino). Currently, I think I will use the Arduino to to activate small electric motors that will mechanical switch the lightbulbs on and off.

Does anyone know how commercial disco lights control the rapid flashing of the lights? Is it mechanical or is it electrical?