I had a customer bring in two identical repro crappies with broken fins. One has a broken tail fin and the other does not and vice versa with the anal fin. So if I can make a mold of the good fin I would be able to use the cast fin on the one with the broken fin etc. What would be the best material to use to mold these fins? I would like to use Bondo, so would a vaseline release work or Syn Lube? Or can I make a two piece alginate mold? I already have the material to cast the fins out of.