Meh its hard to use cardboard when we're in the rainy portion of summer. It takes me about a week to use a tank of gas, and I would like to slap on 4 aero pieces in the first go. Well Five Aero pieces, 4 are fiberglass products (in my mind at least).
The coroplast seems like an interesting way to build forms for fiberglass though. I am wonder where is a good place to source or individual pieces? I did some quick search and I can buy it by the pallet, but thats a little excessive.
I also know there is a certain type of hobby plastic that works well for vacuum forming, but I need to look that up again. I think vacuum forming over some simple carved foam shapes will yield an item that is replaceable (stones, birds, jackass in parking lots). Not to mention lightweight as well!