Keith,
I'm thinking aluminum sheet cut from disposable pie and cooking containers. Tom Morgan told me he sources much of his scratch building stocks from these and I bought a lifetime's supply at a local "Dollar" Store after hearing about it. It will be a while before I get to my Fokkers however when I saw this reference earlier I thought I'd try them using the aluminum; thin, cheap, pliable, and easier to manage then the beer tin aluminum I would think.
Cheers,
Lance