On another world, there is giant ravine leading into a cave where a sentient species live (Let's call them Cavers). They have limited access to materials; the only resources they have are rocks, metal and sometimes unfortunate animals that fall into the ravine.
The Cavers have made drum and xylophone-like instruments, smelting out the iron from the rocks around them and hollowing out the iron to be hollow with a specialized drill-like tool. Occasionally when an animal falls down from the surface, musicians may collect the pelt and use it as a leather covering for their drums, making the sound richer.
The most recognizable instrument invented by the Cavers is a mix between a water mill and a music box. A huge metal comb sits next to a giant cylinder, which is turned by an underground flow of fresh water. The pins on the cylinder continually play the Caver anthem, to the point where most Cavers have accepted it as background noise.
Is all this possible to do in real life? If not, what should I change?