Website: electrotechnique.cc
The pcb and front panel to build TSynth will be available around May 2020 from Tindie with SMD 4067 multiplexers, 6N138 opto-isolator, capacitors and resistors fitted. The entire cost of parts to build TSynth will be around $99 if you buy components from the cheaper suppliers and the build time around two hours to solder. Plans for a 3D printed/laser cut enclosure will be available. Questions: [email protected]
The source code requires Teensyduino from PJRC to compile. You also need CircularBuffer from Agileware and Adafruit_GFX, which are available in the Arduino Library Manager. The latest TeensyDuino v1.54beta9+ appears to work fine now.