Originally Posted by theBongolian
I can't find aluminum panels locally (Seattle).
There are several sign shops and sign supply shops in Seattle that should all have some kind of ACM panels for you. Grimco.com in Tuckwila being the most likely to have the best price on Max-metal ACM which I believe is their own house brand, but you will need a business license to buy from them.
Take a couple of card tables with you, a craft knife, fine point marker and a 48" or longer steel ruler / straightedge and you can easily cut them in the parking lot to fit in the backseat or trunk if you don't have a truck.