You can use styrofoam (use styrofoam glue to glue bigger chunks of
styrofoam together) and easily carve (electric carving knife,borrow your
wife's electric carving knife from the kitchen) and sand whatever kind
of shape you want and fiberglass over that.Gasoline will melt the
styrofoam but will not affect the fiberglass.There are fiberglass cloth
materials available at boat/marine supply stores,the fiberglass
stretches over/around odd shapes like a sweater.
cuhulin