Hello, I’m surprised nobody noticed, there is a new DIY programmable midi controller from blokas.
It’s called the Midiboy : https://blokas.io/midiboy/
From the website :
Specs
8-bit ATmega328P 20MHz Microcontroller
1.3” OLED Display, 128x64 Pixels
2 x MIDI DIN-5 Ports
6 x Tactile Buttons
Piezo Speaker
Powered via USB or 9V Battery (up to 16 hours)
Comes as a DIY Electronics Kit
Dimensions - 100x66x39mm
Arduino Compatible
I ordered one, I’ll get back to you on how usable it is.