Tiny USB Knob
Sends HID or MIDI commands via USB
Firmware update instructions are here
Overview
This is a very simple device with a rotary encoder and a cheap USB microcontroller. When you twist and click the encoder, it sends HID or MIDI commands to the host depending on which firmware version it's flashed with.
The HID or MIDI commands can be configured using web configuration tools. These were built with Vue.js and use WebHID and WebMidi to talk to the devices.
Originally I built this just for myself but since putting it up on Etsy it has sold quite few.
Instructions for flashing the firmware are here