I enjoy making electronic music, especially modular analog synthesis, and a few years ago I started to build electronic instruments and modules myself. Here I list a few projects in various states of completion.

This is a rather complex MIDI sequencer, with USB MIDI interface, multiple hardware MIDI in and outputs, Ethernet/OSC connection and Control Voltage/Gate and Trigger outputs for use with my modular synthesizer. Based on the excellent work of Thorsten Klose.
Status: Functional
Everything works, I still need to connect all the analog outputs, and no it is not going to stay in this ghetto case, I’m going to build it into:

Case from Hammond Mfg.

This is the Core with an STM32 microprocessor onboard plus the USB and MIDI interfaces.

Ardcore
This interfaces an Arduino Nano (mid left) to a Eurorack analog module, allowing me to write all kinds of programs, uploading it via USB, and using it in any way I want. Building two of these.

Status: Waiting for final parts

Serge VCS
A classic. This is the CGS version.
Status: Functional, but it doesn’t cycle, going to check the transistor pinouts.

CGS Slope Detector.