I have never made a folder and don't plan on if for eons yet. And, I don't know if there are different kinds of aluminum or not. But I will tell you a good source of small quantities of aluminum and brass and if it is the right stuff (i.e. more knowledgeable people here say so!) then you are in good shape. There is a hobby shop that sells plastic models and train sets near my house. They sell small sheets of brass and aluminul (the best I can remeber is that the sheets were about 3" wide, upto at least 1/4" thick and around 12" long. They aslo have all kinds of tubing and rod for making mosaic pins, thong hole liners, etc. JACKPOT!!!!
------------------
"Come What May..."