My original plan for this build was to make an R5-D4 because I wanted to build as much from scratch as possible and I knew R2's dome would be a challenge. Once I got pretty far along with the build I realized that I had to do an R2 and this would require purchasing some pre-made parts. Some people have experimented with "found" items as a dome, but it's hard to find something that is accurate, especially since R2's dome isn't a perfect sphere, it's actually slightly egg-shaped.
For my dome I purchased the custom made styrene dome from Granite Earth.
https://www.graniteearth.com/ProductDetails.asp?ProductCode=Plastic-Laser-Set
The dome comes in three parts, a laser cut outer layer, an uncut inner layer, and the dome ring which goes between the dome and the body.
The first step in preparing the dome was to cut out the inside of the dome ring. To do this I used a spiral cutting bit in my Dremel and a cutting guide. The cut will never be seen so it doesn't have to be perfect. The bottom edge of the ring also needs to be trimmed. You can see in this picture how it flares out, that pieced needs to be cut off. I did this carefully with an X-Acto knife.
Here is the cut ring.
The outer dome comes with all it's panel cut out, but still held in place with some small un-cut tabs. I wrote a number on the back of each part and also marked up a drawing with the same numbers so I would know where each piece goes. I then cut out the panels and sanded off the tabs. The cuts on the outer dome had a bur around the edges of them so I had to do a lot of sanding to get all the edges clean.
The next step was to cut the inner dome. I started by using the outer layer as template to mark the inner layer where holes need to be cut.
These cuts don't need to be perfect since the outer skin will hide them, but I still wanted them to be pretty clean. I started with the Dremel again, but didn't try to cut right up to the line. I then used files and sand paper to clean up the holes.
Before assembling the dome I needed to determine how the details would be mounted on the dome. For most of the details, like the holo-projectors, I drilled holes so I could glue in some small, flat head bolts.
I then counter sunk the holes so the head of the bolt would be flush with the surface. I then used superglue to glue in the bolts. The outer layer will also help hold them in.
