Waterdrag0n86, I'm soon to be starting a foam build of N7 armor, also using Hugh's files. Over PMs, he told me he used approximately 10 sheets of EVA, counting several major remakes of pieces. I'd say buy 12-16 sheets just in case you mess up a few parts, or decide you want a different armor part, say, Hane-Khedar(spell check?) gauntlets or something like that.