After a fruitless search for cheap honeycomb sandwich aluminum I went with .040 sheeting.
I bought the material fromhttp://www.researchalloys.com/home.html">Research Alloys, that place is stuffed to the gills with weird metal in all shapes and sizes, everything available for scrap prices. $20 got me what I needed and they sheared it to rough sizes so that I could haul it home in my e30.
After shaping the three sections using cardboard templates I took the sheets to a friend’s aviation shop and had a go with his bead roller. The machine was pretty basic and operated with a hand crank… some of my beads ended up a little wiggly.
My day job is working on bmw’s in an independent shop, some of the mid 90’s automatic cars use 6mm bolts to fasten the transmission pans, trans filters for these cars come with new bolts. I saved a bucket full of the used bolts with the intention of using them for something nifty… firewalls are nifty. By careful use of the WAG method I determined that the firewall sheeting needed a bolt every 4 inches, this meant I needed to drill and tap about 120 holes. I welded a 1/4” drive socket to a cheap tap handle, tapping was still a pain.
I still need to seal the edges of the sheet, I may paint them and add some sound deadening material as well since the panels are quite boomy despite the beads.
