Re: Wall Panels...
Good idea using corplast as template and I second using the fiberglass product from HD. This stuff is resistant, light, flexible so you can curve it at the top and cheaper than Seaboard. The only plus with Seaboard is that it can be structural unlike the fiberglass product.
There are other place where it can be found for cheaper than HomeDepot and in other colors as well (HD only has white).
2001 E350 AmbuLand
2008 E350 AmboEvo
1965 Econoline Travelwagon
1970 Econoline popup camper
A few bicycles...and sandals ;)