K8200 anti-Z-wobble and X-workspace improvement

I have made Z-couplers and all the other stuff here to solve the Z-wobble problems. It changed a little but it was not a solution of this problem. In black despair I have made stability improvements
of the gantry.
see the before-after photos. blue is before, red is after this changes. (ABS, vaporized)

1) holder of the Z-rod. This rod is moved around the right z-profile. [zrod_r.scad]
3) M5 rod between 1) and corner of frame
2) holder for Z-axis linear bearing [zbar.scad]
4) piece o