get a tune in a brass lighthouse

hi folks.

i have a brass lighthouse that is about 15cms high. I have had since i was born and played with it loads when i was a kid. Now i am 42 i have had it chromed, drilled out the lights in the top and inserted a 12v bulb inside. Its sits on a shelf on my boat (canal cruiser) and i flick a switch and it lights up. I would like to mount it on some sort of hollow little box or plinth and make it play a tune like drunken sailor when i flick the switch. Anyone know how i can do this> thought about music box mechanical but these are clockwork and i really need low volt dc?

They make little music box kits that you can put together with relative ease.

Your best bet might be a small, cheap MP3 player (you can get them under $10 now) and a little speaker to go with it.