So Dave and I (mostly Dave) Spent about 8 hours shaping an Eg hatch wing with bondo and fiber glass to fit my wagon. Then another 2 or so sanding and painting it.
Laying down aluminum tape and putting wax on it allowed us to mold fiberglass on the car and be able to remove it easy without ruining paint.
laying down the fiberglass
shaving/trimming the wing to make it fit better. notice the lack of the 3rd brake light.
molding the spoiler to the fiberglass base on the car
after it cured, we trimmed all the excess fiberglass off and molded the edges with bondo
now its ready for paint!