The sanding time saved on the trim was lost on the pie panels at the top. With R2-D2's panels having enough contrast between the blue panels and silver dome the fiberglass mold Todd Bixby uses doesn't need to have much definition. My imperial droid will be black panels on a black dome, so I needed to make the groves deeper. I tried everything from the Dremel cutting wheel, wood carving tools, and sand paper folded into corners, but this engraving bit for the Dremel seemed to work fast while keeping control.
The last piece for the night was to see if I could get the dome to spin on the frame. Using an 18" Rockler bearing from a local woodworking shop and an 18" floral wreath (particle board base) as a support ring in the dome. I drilled holes in the six bolt pattern on the support ring using the inner ring of the bearing as a template and connected them with 2" bolts and an extra set of nuts to adjust the space to help hide any imperfections in my cutting, mounting, or potential warping of the dome. I did leave it in my garage over the last summer and winter. Here's a video of me spinning it by hand.