This is a music player I made for my entry for the 2013 Ottawa Mini-Maker Faire. It’s based on the popular 555 timer chip.
My main design criteria was that it had to be far more robust than my previous music player that used pencil marks for the resistors. Those pencil marks wore away from the paper moving over them and taking away the pencil lead.
It was an overwhelming success, basically going through 14 hours of almost constant play at the Maker Faire, not to mention being cranked vigorously by countless kids (though I did have to repair the crank early on.)