Gummiship, I used stretched sprue for the shells along the turret top for my King Tiger. Just stretch it, cut them, glue them and then paint. If a little paint gets on the ground work, its ok, just go back later and touch up around them with the base color. Here is the result on my KT.

A light wash around them will help bring them out as well, and also help hide any "extra" paint that might get on the ground work. Hope this helps. "Q"