The material I used was from these metal shelves that I had as scrap. Metal gauge is 18, so it's not terribly heavy, but pretty solid. I have a Hobart 125 rd flux core welder, perfect for the projects I do at home. Other misc tools used were, peanut grinder, 3" disc cutter, dremel (for cutting the keyhole and range finder small cuts), few different body hammers and iron body shaping blocks (don't remember real name) and wire brush wheels to remove stickers and surface rust.
Working on it was super fun, very time consuming, but worth the experience in fabrication and machismo points for a metal Boba Fett helmet. So far it has impressed one lady, Hoping that it will soon impress the ladies. Haha
Build on my friends.