I see.

-IMO is very bad idea to lay the machine on anything else but steel. I will advice against it. I mean the orange part as you have drawn it is bad idea.

-I agree the design should please your eye. I wouldn't do it that way at all as my moto is "maximum efficiency, minimum effort" . I mean i advice against using steel tubes at all. Though as i see it the gantry could be left as it is if you insist on keeping the design, just take care the plate bellow the rails to be truly all supported, not hanging in the air.

-The sides definitely could not be as they are now


I mean, change everything, but if you insist keep the gantry