I went down the rabbit hole on pipe organs some years back when a school I was working at didn't have working bells (ridiculous, I know) or synchronized clocks.

I went down the rabbit hole on pipe organs some years back when a school I was working at didn't have working bells (ridiculous, I know) or synchronized clocks. The simplest organ pipe is basically a big-ass whistle. Besides the metal ones you see front and center, there are also wooden ones that are typically square in cross section and have a block and labium exactly like the recorder you may have been forced to play in elementary school. A recorder is basically a whistle with some extra holes so it can play different notes. I got as far as building the pipe, buying a thrift-shop vacuum cleaner, hooking the hose out to the output end, scrounging the circuit board out of an extra USB keyboard and soldering a solid-state relay in place of the scroll lock LED (inspired by the bit in Cryptonomicon where the protagonist uses a keyboard LED as a Morse code output), and starting to hack some code together to turn the vacuum cleaner (via the keyboard/relay) on and off on a schedule before I decided that I wasn't going to become a teacher after all. I never did hook it all up. All this to say: getting a single note instrument that makes some kind of noise and isn't tuned is ridiculously easy if you don't care about the noise you make creating the required airflow and don't involve a computer.