I’m putting a fuel cell in my trunk, so I guess it is time to put in a rear fire wall (I assume it is an NHRA requirement, but I have never checked). My question is, what materials do most folks use for the fire wall (aluminum, thin sheet metal, etc,), where did you find said materials, and how did you make it?

I’m thinking of just starting with a piece of cardboard to make a template from the back seat area, but I was not sure where to get the metal (or what kind).

Thanks in advance for any help or pointers you have.