This is probably the ugliest ghetto fix I could come up with, but it woked just fine and I’m happy with the result.
My prints in PETG were far from accurate, my entire build was pretty off, XY were not perpendicular so evidently you could tell it by just looking at it, and the Z axis was not perpendicular at all, with a 10cm bracket attached to the spindle you could see more than one cm of height from one side and turning the spindle 180° the bracket could touch the working plane. Also every channel for the pipes was extremely tight and I could feel a lot of resistance to the movements in every direction. Ugly.
What I did was to put belts on the machine and tension it all in place, XY squared and with the Z axis perpendicular, then I heated up the plastic parts with a hair dryer. After everything cooled down I removed the belts and after repeating the process 4 or 5 times, each of the issues was fixed. I’m very happy with the result and I wanted to share it with you, maybe somebody else built something ugly like me and he’s happy if his MPCNC just works good enough to start playing with it, instead of re-printing and re-building everything.