proper way to build custom gauge housing

[GRNOVA]

Hey guys, I am trying to come up with a way to fabricate my gauge housing but cannot figure out how to attack it. What do you guys do when fabbing something like this? What methods, metals,welding techniques. Here is what I have a 65 Nova Dash that I am trying to make recessed for 2 7" LCD screens.The problem I am having is the metal is to flimsy and has to many ripples or does not follow the temp correctly.







Thanks