Broke said:
I remember seeing an episode of Overhaulin where they did this. They used a flexible body filler. After it cured they brushed it down with resin while laying a poly fleece material over the top. More resin on top of the fleece and a bunch of sanding once it dried. I guess thats the same stuff the tuner guys use to make those custom shaped speaker enclosures. I have a spare dash I've thought about trying it on.
Fiberglass resin will not properly adhere to the stock vinyl dash. All of that will eventually fall off.
If Anything you could get a yard or "ponte" 100% polyester fabric, its much thinner and uses up less of your fiberglass resin VS. the commonly used "felt" fabric. Spray the whole dash with a good high temp contact cement(think something along the lines of headliner glue) don't use anything in a spray can, the resin will release the glue of a spray can. Wrap the dash in the "ponte" fabric as if you were wrapping the dash in leather etc. Then apply your resin to the fabric, then a few layers of chop mat fiberglass. Then all body work and paint from there on.