In the digital age you stumble on concepts analog in their nature. Modern graphics are created on a computer yet they originate in an analog process. You constantly change the brush size yet the computer allows you to do it in an increments. Do you actually care your color is R=53, G=123, B=200 in numerical values except when moving the data?
Concept of making an analog controller for art creation on the computer was always interesting for me. An exercise in this was this small controller built with Arduino. It's just a 3 potentiometers dividing voltage. Arduino reads this voltage and sends the numeric values to Blender which can use them in various ways thanks to built-in Python environment. I used it to control color values.
Below you will find an explanation in a video form.
I have also wrote a blog post in the topic of human-computer interaction which you can find here.