So I kept working at it.
Introducing the Cave Construction Kit! This is just the beginning. Below you can see a good assortment rock models that can be combined to form a variety or great looking 3D rock formations. This kit can be used for caves but can also be used for any outdoor environment which requires boulders, cliffs, crags, and any other rocks.
I decided that hand sculpting the rocks was the way to go. Now to put together a cave!