Don't forget carboard and duct tape for the prototyping.
RoadWarrior. Great idea on the plastic buckets and jugs. Last weekend I built a cardboard template for deflectors to go in front of the front tires. But now I'll be eyeballing square jugs and buckets for just the right shape. I think that will look a lot better than the Coroplast I intended to use. (LOL, just thought of a new thread, "what trash looks best on your car?") Hmmm. I'll have to look at plastic tubs for aero hubcaps. Maybe the bottom of a laundry basket. Yeah, that would be cheaper and lighter than the aluminum pizza pans.
I don't think you want to deflect air behind your minivan with the 1/4 noodles. The best method is to get the air flow to separate cleanly from your vehicle, either via a sharp lip, ala Kamm back, or with vortex generators. Speaking of that, does anyone know where I can get some wedge shaped rubber molding which I can glue around the back end of my car to create said lip?
VetteOwner, where did you get your flashing? I checked the mega home center this weekend, and all they had was lots of galvanized steel and an roll of *heavy* aluminum, which was about $40. They had a roll of some nice lightweight plastic flashing too, which might be useful for some aero mods. But I was shopping for belly pan materials. Maybe some aluminum trailer skirting...
BTW, I just realized last week that you're driving a Chevette, not a Corvette. Duh! LOL. Okay, back to modding...
I got some rubber molding from the Home Depot last year, which I've used to reduce the grill opening (see garage pic), and for a wiper blade cowling. Also visible in the pic is the the foam weather stripping RW mentioned, used to sealed between my hood and headlights. I also sealed around the headlights tough UV resistant tape. Folks have also used plastic wall panels (for shower or kitchen walls?) and aluminum window screen for belly pans. Pizza pans for hub caps. Dryer vent for WAI. Peanut butter jars for PVC catch cans. oh, I"m getting off the aero now