simple DIY 555 synth

Youtuber sycmuzak posted this demo/explanation of his breadboarded sound circuit –

My homemade 555 timer synthesizer. I made it in about 2 hours from 2 555 timers, 4 capacitors, 1 resistor and 3 potentiometers. Schematic can be made available if demand is high enough. This is one of my first 555 timer projects, and I’m a high school sophomore, so feedback is appreciated.

It seems demand was high enough to warrant a schematic posting. Looks like fun –