I countersunk 4- screws into the skin to hold the Octagon Port in place and then I used Glazing putty and Bondo to smooth the edges and hide the screws. Now I know this is a permanent way of mounting the Octo., But I studied the pics and the blue around the edges is suppose to come all the way out to the skins instead of stopping just before the skin area and having a white ring around the Octo. Right now your seeing the primer and as soon as skins dry from sanding I'll start the painting.
The Coin Slots, I decided to go with the blue around the sides and bare aluminum on the ends. Someone told me since I have a shinny dome that my R2 looked more like the Empire Strikes Back version and from the pics this is how it looks. There is some loose paint from edging around the ends down inside the gaps, But this will be behind the skins and won't be seen so I didn't worry about getting the droppings out.
I'll post more pics as soon as I get the skin painted and hopefully it turns out nice.