what are goaltending masks made out of?

common mask materials are:
glass fiber, carbon fiber, aramid fiber(kevlar) and the all important resin (holds everything together)

each has their upside and downside:
fiberglass: cheap to produce, relatively pliable, heavy in weight, easy to work with
carbon fiber: expensive to produce, very stiff, light in weight
kevlar: expensive to produce, stiff, very light, notoriously difficult to work with

Each fiber also comes in various grades, weights and weaves, affecting the end product, as well as how it interacts with the resin it is used with.

mask makers agree that the resin used is as important as the fiber used. common resins used in mask making are: polyester, vinyl ester and epoxy.

again, each has their ups and downs:
polyester is the cheapest, but has the lowest bond strength, suffers from eventual breakdown
vinyl ester is more expensive, a stronger resin but with only marginally better bond strength, still suffers from breakdown
epoxy is the strongest, is very expensive ($50-$100 per quart), doesn’t suffer from breakdown and is difficult to work with (needs vacuum forming vs. “lay up”)

each individual mask made has different proportions of fibers and resin used to distinguish the product (both in strength and price). that could mean two layers of aramid with two additional layers of carbon fiber with a finishing layer of fiberglass made with an epoxy resin. vs. single layer of aramid with a second layer of aramid on spot impact zones (forehead, chin flare) finished with fiberglass with a vinyl ester resin. manufacturing is interesting!