I have a large sheet of aluminum to make the firewall between my trunk and the passenger compartment. Looking for fabrication hints.

I've considered going by a furniture store for a mattress box and making a cardboard template. Or cutting an approximate shape, fastening it either at the bottom or the top, and trimming to fit as it goes.

Any tips?
thanks.

Yes make a cardboard pattern first. Install it from inside the car, not the trunk.

take your time & cut/trim/drill holes in it dead on the way you want it then transfer em so you only have to fit it in there one time

that.......

Construction paper is easier to work with than cardboard.

Excellent idea

Aluminum wont stop a fire, stainless and steel will....

Where do you get it in 30"X 60" sections?
Cardboard in that size can be found in almost any homeless camp.

that crossed my mind too that he might need to tape/glue several pieces together

bought construction paper from Walmart and taped it together to make it large enough...

my car came with a hard card panel behind the seat sealing off the trunk---bet it would make a nifty pattern for the trunk firewall----bob

Stainless steel, traced the old divider onto poster board first.

I use pieces of poster board taped together when I have to make a large pattern. Poster board can be had at 99 cent stores, kmart, wallyworld etc. Very inexpensive. Making it out of stainless instead of aluminum, for fire resistance, may be a toss up as the aluminum should be way more resistant than cardboard and plastic upholstery. But aluminum does melt at a lower temp than stainless. Choices! I wonder if you added some heat deflection material to one side of the sheet it would help on the fire issue plus you may pick up a sound deadening benefit.

If you are really worried about fire, make sure to plug the holes in the package shelf. Then there is always the area between the i/4 trim a whel tub.
Doug

I'd make the pattern so it is tight all around so it is sealed off pretty much completely which I believe is what you are after

That is the idea, to seal off the trunk, as mandated by NHRA rules for any vehicle with a trunk-mounted fuel cell!

The package shelf is also required to be closed off (since it has large openings for speakers). If my 4' aluminum sheet is wide enough I may make it in one piece. I think I'll rivet it in place and use seam sealer.

After some more searching, I found the original cardboard divider! It was a good starting point (to locate the holes for the seat hooks and reproduce the top curve), but since my car is minitubbed I made the aluminum wall 3" wider to sit on the flat front of the wheelhouses rather than taper between them. It'll be easier to seal that way too. So far it's held in place with Cleco clamps, the wiring harness and battery/alternator cables are run through firewall bushings, and I'm trimming the bottom to fit the floor pan before permanently riveting.

Unfortunately I can't locate the original package shelf, so will have to draw that long smooth curve another way. Going out of town for a week, more later

It's not supposed to be a 1 hour fire barrier. It won't burn up similar to a firecracker fuse if made of aluminum.