Some projects simply leave you in awe when you consider the thought and the amount of work that went into it, not only for the actual implementation, but for everything surrounding it. Even more so when it’s a one-man open source project. [Stone Prestonsynth ]’s / sampler / sequencer / DAW-in-a-box LMN-3 fits the bill perfectly, and it appears that he has made it his mission to ensure that everyone can build one for themselves by providing all of the design files, right down to the keycaps.
The LMN-3 (pronounced “lemon,” not “comes before the OP”) is a standalone, portable digital audio workstation based on a Raspberry Pi 4 and a HyperPixel display for the user interface. The Tracktion Engine was used to create the UI and the core part of the software, which combines your typical synthesiser, sequencer, and sampler features with the DAW part to handle recording, editing, and mixing. The remaining hardware consists of a custom-designed PCB with function and keyboard buttons, a pitch bend joystick, and four rotary encoders with push buttons that serve as main input handlers. And a Teensy board, of course.
The UI is entirely controlled by MIDI commands, with custom firmware on the Teensy translating input events from buttons, encoders, and joysticks accordingly. This effectively separates the hardware from the software, and by utilising a cross-platform framework underneath, you can also run the UI standalone on your computer and use any third-party MIDI controller you desire. Or, as [Stone] considered everything, use a hardware emulator he created in addition. You could even remove the Raspberry Pi and software entirely to make this a pure MIDI controller. If that sounds appealing, but you prefer something with more knobs and sliders rather than buttons, consider the Traktorino.