I've been meaning to post this here forever, but I guess I really really suck as a saleslady... I worked with some friends/colleagues here in Chicago a couple of years ago to make an affordable Teensy-based MIDI/CV converter and flexible experimental control platform (Eurorack compatible). It isn't profoundly unique, nor cutting-edge, but we've found that it is a very handy little device for placing between other parts of an experimental soundmaking system. I really like using it with Axoloti to let Axoloti-based signals control an analog synth. The Betweener was built with a pedagogical context in mind... I wrote a simple support library for it which is very heavily commented, for a student audience.
All info is open source of course but there are a few kits available too, and all the links are in the page shared below.
Thought I should finally post this...for a summer when maybe a lot of people are going to be stuck in their houses more than usual, needing projects?