I'm working on a side project, and I want to generate a static and crackling sound on my hobby speakers. I've noticed that if I connect the positive wire from four AA batteries to the back of the speaker, and then slide the negative wire back and forth across the other lead on the speaker, I get exactly the sound I want.
My question is, can anyone suggest a component I could use to simulate the same motion, or another inexpensive way of doing this? The entire thing is for a costume, so it needs to be compact and lightweight.
Thanks for your help. :)