Great question! If you're me, alot. I am using a mixture of Aguilar Workshop, Galactic Armory, and From The Brink files for my ODST and I have gone through 15, going on 16, spools so far. The armor itself took around 10-12, but through prototyping, failed prints, support material, and other props, I've gone far past that. Like the others above have said it depends on your physical build (tall, short, skinny, large, etc.) but I'd allocate for at least 10-12 rolls.