Use the power of touch to control the show!
Animus is a beautiful music visualizer for mac os made with Processing. There are a number of keyboard shortcuts to adjust the visualizations, but instead of a computer keyboard, you can use a custom touch controller you design and build yourself. Coded with CircuitPython.
This project uses the MPR121 12-key cap touch sensor STEMMA QT breakout as input for a QT Py, which will act as a USB keyboard device for your computer.
The great thing about this project is there's NO soldering required - you can plug-and-play the capacitive touch board into the QT Py using a simple cable connection - and then use copper tape to make the pads!
You'll also need some cardboard or other surface to affix the controller. I used a 18cm wooden disc from a craft store (shown here with copper tape applied).
Glu Dots or double stick adhesive tape works well to secure the QT Py to the board.
If you want to print a graphic overlay, you can use some spray mount adhesive to secure it.