I had totally forgotten
 

I had totally forgotten about those pics! I wonder if that support bar thay have going down the middle is really needed?? I dunno if the bumper support bolt holes can support the entire weight of the car or not. I'll probably just jack the car up about 3-4 feet so I can keep the bumpers on while making the tray.

Re: Way cool! Where can I get
 

I have tried Lowes and Home Depot. When I ask about it they just look at me and say huh? The closest thing I found was pre printed house for sale signe, 24" x 30". Not big enough.

Any other ideas?

You can use aluminum
 

You can use aluminum flashing if you figure out a way to attach the strips together or just do a bit of overlap.

try a sign making shop.
 

try a sign making shop. they often use coroplast (as you found, pre-cut). just beware of pricing.

i first located coroplast locally at a sign shop, and they would have happily sold me as many sheets as i wanted at $40 per 4x8.

fortunately i was just hunting that day, and didn't buy; i found out not long afterwards it's about $20 per sheet at home depot.

While I was walking through
 

While I was walking through Home Depot I was look=king for other potential materials. I found 2x4 ft flouresent light covers in styrene, and in acrylic. Seemed too thin and brittle. I also found a 4x8 ft sheet of plastic pegboard. The holes could act as dimples? Anyway, pretty heavy stuff. Then I saw the vinyl siding. Lightweight, cheap, flexible by rigid when pieced together. A good candidate as long as the seams are aligned in the direction of airflow.

Any thoughts from the aero gurus?