Custom Midi Expression Controller

Here is a Midi expression controller that I built using an 'Arduino' microcontroller (a Pro Micro to be specific). It contains two faders and also a rotor. These are things that are found in studios to control the dynamics and expressions of sounds when mixing songs.
In this video, you can see me playing the French Horn using a keyboard, and controlling it's dynamics and expression using the contraption that I have built. This whole concept of "Home Studio" works because of a fascinating technology called Midi, which is a digital representation of music. The keyboard sends a Midi signal to GarageBand saying what note I am playing and at what speed. My Expression controller sends the values of the faders and the rotor to specific Midi channels, to GarageBand - Expression and Dynamics. The plugin I am using for the French Horn patch is called the BBC Symphony Orchestra and is made by Spitfire Audio. This plugin, receives these Midi signals from GarageBand and plays the corresponding French Horn sound.
The work my expression controller does by itself is simple. It has to just read the resistance values from the faders, and relay it through USB in Midi language. But there were some challenges involved - the faders I got were logarithmic! That is, the resistance changes logarithmic to the movement. I had to change that behavior to linear using code. I also had to handle erroneous and wild value changes too (which were frequent), using code. With Midi, one can also make a simple keyboard, using a similar Arduino and lots of good buttons!
You will be able to understand why these expression controllers are useful to music when you watch the demo video. Make sure to use good stereo speakers or headphones to give justice to the divine French Horn!
Lastly, note that I will give additional points for those who figure out what I am playing here!

[@infernapeDLS]

nice, do you know of any good midi expression controllers on the market?

[@harir3]

I am not the best person to call that out as I have not tried any. Since I have built it and it was pretty easy and straight forward to do so, my hunch is that pretty much anything should be good enough. However you can also have a look at the video here - czcams.com/video/Br68rBLanmo/video.html