Just came across this board today and immediately thought of this project when I saw it. Have you thought about trying to use this to help with getting the MPCNC as a 3D printer working with this autosquaring system?
It’s $40 + shipping, so it’s on the pricier side, but it adds 4 additional stepper motors, as well as a ton of other things and allows you to keep your lcd screen. Interested in hearing what you guys think about it.