petrifiers can be used to stablize the existing/remaining soft materials. then a filler can be added to shape and sanded to a final finish. i know epoxey fillers are superior to anything i`ve heard of, but i`ve not had any luck with them. the next step down seems to be bondo as a filler. a little more user friendly and have had good luck with it so far. should be enough to get you a start. gd lck.