Warning, the squiggles on the San Diego replica look HIDEOUS and are nothing like what you see in period photos! In fact it looks like they had some kid finger-painting on it. The squiggles need to be much denser and are also of a different, smaller, and more random shape. I did a lot of practicing on bits of scrap aluminum (definitely visit the Dollar Store nearest you) until I had a pattern that looked right. Some of my early experiments looked a bit too much like Arabic! Finally, I started to try to think like a factory worker who has to do as many as 10 of these each day and just sort of settled into a mindless routine of filling up all the cowl space with short bursts of squiggles (about 1-2 seconds each) with the electric eraser.