I wasn't aware that any of the filming models might have used anything but the koolshade material. Are you suggesting that they made resin versions of the koolshade?
Steve sourced enough of the newer koolshade for at least 5 TIEs back in 2006, and there was just a group of 13 orders recently filled by Matt (dragnink) for the vintage stuff. I don't remember how many were in Matt's previous run but it was probably about 20 so there's at least enough koolshade out there for 35-40 TIEs.