I'm still not sure how I'd suspend the orb (which is essentially the case) but in its current state it would just collapse. I found this article on Tom's Hardware about water cooling so that should help (only read one or two of the eleven pages). The "water cooling box" in my diagrams is the reservoir (I think).
Tomorrow I might be able to get some better drawings down. Rough ones like I've posted helped me get a good idea of the form. For anyone whose used UnrealEd they might know about the tool that blurs everything so you can see the flow of colours in the map, it's a bit like that.
The base is attached to the head through the pipes, which are mainly metal pipes (like those in the ORAC case mod, don't know what they're actual name is) and a few water cooling pipes. The water cooling pipes would need to be extended somehow to reach from the base to the body. If you look at those pictures of sentinels I posted before, it might better explain my design.
Update
I've done a couple of cleaner drawings, which I'll try and upload tomorrow, along with some more if I can.