Below, the dome ring is now painted blue.
As usual, the R2-D2 blue is hard to photograph...it looks lighter than it really is in this photo...
It takes a lot of careful sanding, grinding and filing to get the hole sized right for the HP. Once lined up, its just a matter of drilling the holes, countersinking them and bonding the screws into position. The outer dome will lay flush on top of this one, so the screw heads, bonded into position, will be sanded to assure a good fit.