Re: MiniDisk? Bah!
MiniDisk,. wax cylinder? For years there was an ornate box sat at the top of our stairs that was a Polyphone.
It had a clockwork motor and played metal disks about 14" in diameter. The disk had small rectangles punched out that were bent down. These then pushed against some small toothed wheels that plucked steel things causing them to vibrate. Hey presto, music (of sorts).