This project was the main part of my MFA thesis project, Beep-Boopatronics, which you can take a look at here.
The 3D printed parts here are sized for the instrument pictured, and these servo motors from Adafruit. The tolerances are pretty tight, and so you may need to drill out some of the smaller holes in order to screw things together. The code for the project can be found on github here.
Here is an example of the device playing composition by John Cage, adapted for the chord organ.
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