I'm wondering how I could make an extremely small speaker (ideally the size of a stack of 3 quarters) that played a custom sound, like a 5-10 second music recording. In my dreamland the sound would be timed to repeat every hour or so, and the speaker would contain its own power source. The cheaper the better. Looking for advice on (1) what materials would be necessary (2) where to buy them and (3) how to record the sound and transfer it to the speaker. Any and all advice appreciated.