Effect of Forces on Gantry Cross-Sections?

[JAZZCNC]

For instance if Jonathan were to build a new machine and dosh wasn't a limitation, I wonder if he would still use box section, what size it would be, and why?

If NO DOSH limit then I'm 99.9% confident he wouldn't and it would be a hefty lump of ground cast Iron or some fancy composite affair.!!

Can't hide from the fact box section sings like a canary and resonance and vibration are to be avoided so density wins every time, that's why cast iron's used so much.

This is the kind of thing you'd buy(New) if Dosh no limit.!!! . . . .
Here's the Y Axis carriage(pic1) which carries the Z axis(pic2) of my future 5 axis toy(Doubt I'll touch it this year thou.!).!! . . . It's one big cast iron lump with a counter balanced Z axis which is very long lump of cast and ground aluminium that runs along the roof of the main machine frame which is one big structure of steel and ground cast Iron.. . . Very very very strong and heavy 3.8ton the frame weighs.!!