BTW: with a software tweak the same hardware can be used for movie or music editing. You could then turn the knob to adjust the movie playhead position and press it to split the video. You can buy such an editing tool at a high price whereas this project makes you one for a few £ or $.
Credit for this project is due to Josef Prusa of Prusa Research. Prusa make highly regarded 3D Printers using 3D printers. Extra thanks to Mr Prusa for being so inspirational in presenting the project so well in the video below.
What you need for this project
An Arduino pro micro which has a micro USB socket aka “Pro Micro ATmega32U4 5V 16MHz”
A rotary encoder as shown below – this transmits codes (whereas a potentiometer changes a resistance).
A box or 3D printed case
Mostly female-to-male Dupont wires which you might solder or glue in place
A micro-USB cable to firstly upload the code to the Arduino and secondly to attach to the computer you want to control.