After failing to get Jess to buy Rock Band for the house, I decided to get a metronome and use that. Caitlin couldn't find hers, so I decided an excellent thing to do would be to build one. Naturally, in an Altoids box, as anything that could fit inside an Altoids box is always cooler when one has done so. So one 555 chip and a few hours in the basement later, I'm happy to announce success. A relaxing alternative to thesing.
I'm pretty pleased with it; I've been playing a lot of piano and guitar with it the last day or two and it works well. It's pleasantly simple to build: a pair of caps, a resistor, a pot, a speaker, a 555 and a battery are pretty much all you need, although another LED+resistor or two is nice. No need for an amp: a 9V battery gives sufficent volume through the 555.
Look, it looks like everything else built in an Altoids box! Note on/off switch and pot sticking out.
and layout diagram (post-hoc)
Thanks to Caitlin for her help in solderin' and buildin' and all.
I really should get around to writing this up on Instructables so that Christy doesn't tell me off here, but I always forget to document as I'm going along. Ah well, maybe I'll go and recreate at some point over spring break.