Main thing about the eye-parts: DO NOT WORRY ABOUT MATERIALS!  As long as they are different materials, They can be handled later.  The transparent parts are best handled procedurally, anyway.  Fantastic stuff so far!

I cannot save the world. Only my little piece of it. If we all act together, we can save the world.--Nelson Mandela
An  inconsistent hobgoblin is the fool of little minds
Taking "Just do it" to a whole new level!