Some info in here.
http://www.airsoftcanada.com/showthr...hlight=plastic
Apparently it is a plastic that is very durable. I think it is high air to plastic ratio in comparison to your standard plastic, but it is stronger than your standard plastic so I guess it evens out, due to the injection mould process or whatever.
Carl, are you putting these together yourself with other members of AI, or you going to hire a group of people to help you?