Build your own vMix Surface Controller 4 Input DIY based on MIDI Controller
Im using Arduino NANO ch340, (maybe) the cheapest Arduino Board with USB.
4 Preview Button
4 Active Button
3 Transition button
4 Fader Volume Input
1 Master Volume
I already compiling & build with the library to make it simple.
All you do just download and upload to arduino using Xloader
Hairless MIDI :
Loop MIDI :