Tiny USB Knob
Sends HID or MIDI commands via USB
Firmware update instructions are available for PC and Mac:
PC Update
Mac Update
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 the web configuration tool. Note, this tool works on Chromium based browsers (Chrome, Edge etc) but not Firefox or Safari.
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