Lots of companies sell replica light-sabers that light up and stuff, but none of them look particularly convincing when you film yourself swinging them around like an out-of-control Star Wars Kid. That's because the actors in the Star Wars movies don't actually have buzzing wands of light in their hands while they're shooting: instead, they swing sticks at each other, and later on, effects people matte in a rotoscoped beam of light.
This website explains exactly how to matte in your own light-saber effects on your homemade movies, from how to construct an easy-to-rotoscope saber right up to using video-editing software to add the light-beam.
(Thanks, IZ Reloaded!)
