The concentric circles are done with an airbrush and some paper templates- you can see them in the background of one of the Thomas Models pics. You can get a special paper cutter that can cut circles of any diameter at your local craft/scrapbook store like Hobby Lobby that would be perfect for this. The radial lines can probably be taken care of with small pieces of tape.
I've only built the "Mirror, Mirror" version (2nd pilot style), so I haven't tried out the concentric circles yet. Soon though