Just a quick post to follow up on some information that I gathered at a recent home show. I currently have a fellow that is working on a concept car and has been using foam to make the rough shape. As he is planning to fiberglass the resulting model he needed to use a urethane foam (polystyrene foams melt – so they need to be coated first). I this case I think he used the spray cans that you find at the home improvement store (Great Stuff or the like). At the time I thought of nothing better but then at the home show I ran into some urethane insulation firms that spray insulation. Now without a doubt they are more expensive but as they could spray a nice even coat of foam over any odd shapes (one of them had done some parade float work) they would save hours and hours of work on a project like this.
So food for thought if you have an odd shaped project that you are planning to fiberglass directly. Alternatively you could use styrofoam and cover it with an 100% solids epoxy before fiberglassing it with a polyester resin. You could also paint it with latex paint but as latex can bead on the foam, epoxy is a better option.
The firms I saw were Anta Insulation (firstname.lastname@example.org 604-338-9286) and Chinook Insulation (email@example.com 604-309-5972).