 You can build a USB MIDI controller with a custom PCB, Adafruit's QT Pi RP2040, and Circuit Python. This hexagonal-shaped MIDI device lets you play chords with mechanical key switches. It features seven chalk key switches that are backlit with NeoPixel LEDs. You can press multiple keys to produce multi-tonal chords. Each key is assigned several MIDI notes that sound good when played sequentially. The code was written by John Park in Circuit Python and uses the keypad and MIDI libraries. It features a mode select that allows you to change scales, octaves, the root notes, and lets you choose between playing chords or solo notes. Press the QT Pi's boot button to activate mode select. The NeoPixels will turn red to let you know when it's ready. The Ripple lets you know what options to select. You can use the key switches to make your selections. A handy key legend denotes the options. The last option lets you choose between chords or single note playback. And because it's Circuit Python, you can customize the MIDI notes, octaves, and the colors of the NeoPixels. John Park designed the PCB in the shape of a hexagon and features footprints for chalk key switches and reverse-mounted NeoPixels. The QT Pi RP2040 is soldered to the back of the PCB with header pins. It uses USB-C for power and runs as a native USB device, so it'll work with just about any MIDI hardware or software. To make a multi-colored 3D-printed case, we use the filament swap technique with yellow and black colored filaments. John's PCB fits inside the case and gets secured with M3-sized machine screws. We also printed these hexagon-shaped keycaps that are designed to fit chalk key switches. You can make them in either FDM or SLA 3D printers so you can choose from any number of materials and colors. These clear keycaps were made by PCBWay using their 3D printing service. They're made using UTR-8100 transparent resin with the spray varnish option. We think they look amazing combined with the backlit NeoPixels. To get the parts, code, and files to build your own, head on over to learn.adafruit.com. I've been playing a lot with this and it inspired me to create the music that's playing in the background of this video. We hope this inspires you to use CircuitPython for your next MIDI project.