Here is the render.  Again I turned down reflectivity on the outer surface sphere to give it a more cast look.  The booleaned cut outs I used a metal of my making. 

The question:  It would be nice if the booleaned cuts had a machined out look that had some tell-tale mill marks on it, sort of like a drill or milling machine might leave.  How can I make a bump channel image to achieve that or use an existing proceedural??

Side note:  adding even the slightest fraction value to the displacement channel crashes my machine.  Memory problems?