If you have a printer that can handle decals, or access to one, here is what you do.
Use the pattern here to make up a decal sheet on whatever word processing program you have. Be sure to make extra decals. Now, print out one sheet on clear film, one on white. Cut out the roundels on the white sheet, making sure no white shows on the edges. If you go into the red a bit, don't worry. Place these decals on the model per your custom. Then, cut out the decals from the clear sheet. Keep it close to the edge of the roundel, this time avoiding trimming too close to the red. Now, place this decal over the previous one, of course lining up
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