I put together a very basic MIDI controller as part of a demo for my Interactive Audio module. It is simply an Arduino Micro, which uses an ATmega32U4 chipset, meaning it is instantly recognisable as a USB device such as a MIDI controller. This removes the need for additional middleware such as Hairless MIDI.
The six pots send MIDI information from CC numbers 20 to 25.
This has become a useful tool for interacting with Touchdesigner, although a newer, more featured version is on the cards for a future build.
The very basic code used to run this can be found here
