Oijando, please be very careful when assembling the new handle. The "screw stadoffs" as it were" are very brittle. They're at an incorrect angle to the split of the handle, and trying to screw into them puts a lot of shear stress on them. Mine have snapped every time, and I end up using a soldering iron to melt them back into place.
Ghostpilot, what's keeping you from using the revised on the github? I did get help creating a longer version of it. As far as adding more analog controllers, I think you're going to run into issues finding enough inputs on the Pro Micro board. Thoughts?