If you want to build the module yourself, I uploaded firmware, schematic, BOM and Gerber files for the PCB. There are two different versions for the control board, an "original" and a "Thonk" version.
Code (AVR projects): GPL3.0. Code (STM32F projects): MIT license. Hardware: cc-by-sa-3.0 The name "Mutable Instruments" should not be used on any of the derivative works you create from these files.