Thanks again everyone for your input. The willingness of everyone here to help me out and explain things is greatly appreciated.

It is really frustrating getting my head around Nurbs concepts but I really want to crack it after several failed attempts over the years. Moi's user friendliness is proving to be my saviour in this aspect.

Anyway back to the case in point. I understand totally what people are saying but what I can't get my head around is how would I be able to create the shell (exactly how I want it) without doing it the way I have? Starting from a sphere I can't see how I would be able to precisely replicate the shell dimensions I want? Perhaps someone could try and do this and prove me wrong!? Use mine as a template but create it entirely differently?

As for how my model is currently. Danny, how did you achieve the result you had!? That's 'almost' exactly what I want! I'd just like the thickness of the shell to be less. As you said I've broken mine into a smaller part but how then am I to create the underside of it like you've done?

Thanks again in advance!