I might just add in that Andrews tutorials are great for beginners. Even if you're not a beginner you can use his templates as a base for other builds. I'm not sure on how mamy sheets I used for mine, but the helmet was one, the chest base 2, the chest plate 1 at least. If you manage to squeeze as many template parts as possible into the foam you will of course save some too. I'd say start off with buying 8 or 12 sheets. I stocked up on blades and hot glue too, it saved me plenty of time. I tend to use up blades and glue fast though, so unless you live close to were you buy it, I highly recommend you to stock up on plenty of it. Good luck!