Glass help

I am thinking about starting a grille for my truck from scratch. Ive fibreglassed with the mat n resin before, a few times(enough to get the hang of it) but never anything from scratch. Im wondering how i should go about starting this prject?Make a mold?if so out of what? should i even use the actual mat or get some fabric?

i would try a reverse mold. carve the shape you want out of some rigid foam and then make a plaster mold. then polish up and finish the inside of the mold(will save time later) and then put some mold release in the plaster and lay down some glass but make sure its flat...and a chopper gun may help ya.