Just make a mould out of polystryene/wood (whatever) then seal it up with paint, put some release agent on it, and lay on the fibreglass, It takes alot of fkin around, but once u get the mould you could make 3 or 4 of them and sell em on. You could find a front skirt off a japa car down by the river on a saturday morning, take it home and start off by moulding that, just to get into the ball park, and tweak the design for width etc.