I have also built a new version of the upper grille block using the same technique and 2-part polyurethane foam. Here are some pics.
Is anyone familiar in working with fibreglass ? I want the upper and lower grille blocks to be sturdy before proceeding with the finishing touches.
Basically, from what I gathered so far, it is safe for me to used epoxy or polyester resin on the 2-part polyurethane foam; it won't melt it.
Any help would be greatly appreciated !