Depends what your methods are and how heavy you slop it on. Why, do you need to buy it all at once? It really depends on how many layers of fiberglass you do, how tall you are (really), and how thick you like your resin layers. My first (probably totally way off) estimate is at least a half gallon for a full suit. Maybe a full gallon. As for fiberglass, you're going to need, you know, enough to cover all the surface area on your armor. Or 2x or 3x that if you're going to do multiple layers of fiberglass. And then there's Bondo...