Accurate Strong Gantry

[vargai]

99.9999999% Nailed on that you won't be able to weld this up and keep parallel/perpendicular in all planes.

I do not want to weld a U form and do something with frame -it makes my life hard

First of all thank you for giving me a 0,0000001 chance.
This is a design evolution process with analysis, checking, listening to the pointers . I am not able to put a ready for production plan on the desk right now and I am patient and have time. Bad design leads to a better one. (in a good case)
This is still a study where I try to find the place for all the function.

Some detail explained in written form and never meant to weld this construction otherwise I would need medical treatment right now.
Yes, box section is better than C no question-even when equipped with bracing
For some reason I supposed that box section is more inclinable to resonate than a thicker opened one
The stronger the better so I am opened to the closed section
Just a sketch about how I understood double upright braced in two direction