HI kida, i have recently strated to make a gullwing door roof for my Kit car, i used PU foam sheets and then layed up on that. have alook at my build here, mite give you an idea mate of how easy it can be if you are ok with DIY stuff.
http://www.mig-welding.co.uk/forum/t...ng-roof.46306/
if you want more info on how i did it just ask kida.
wolly