R3 Acrylic Dome

I just ordered an acrylic transparent dome for one of my Astromech units. It will come next week.

Now i have to make myself some thoughts about the inner and now visible parts of this droid.

I have a neighbour often having damaged ic boards from various machines. 

This and other parts might work together with cables and unknown other parts to get this typically Star Wars look. 

but first of all i have to figure out how to change the diameter from 500 to 463 mm. impossible you might say ????