So, my niece showed me an "omnichord", I had never seen such a thing before, she had some fun with it, and she really wanted one for herself.
But so expensive! And after looking into it, also quite limited.
So I tried to make one from a Raspberry pi, using sonic pi as the audio engine and controlling it from a qt app with a touch screen. Glued a 3d printed case to the back of the the touch screen. Used glow-in-the-dark PLA with some UV led's in the box to fit the spooky sounds :)

Anyway, after a bit of programming, out came "Luciel's Birthday Omnichord", it can do a lot, many different chords, in higher and lower octaves, inversions, different synths for strum, bass and chords, drum machine, clone it from codeberg:
https://codeberg.org/Grobbelplop/LB_Omnichord

You can also run it on a linux desktop system, installation instructions are in the README file: https://codeberg.org/Grobbelplop/LB_Omnichord/src/branch/main/README.md

Who is going to join the Omnichord players?