I'm trying to learn how to make better ambigrams. As a part of this, I'm learning how to use Adobe Illustrator. Illustrator is a very versatile drawing program. I originally drew my veritas ambigram using Adobe Photoshop; but the fixed-size image produced by Photoshop cannot be easily scaled up. So I traced the original raster image into a new Illustrator document.
To get more practice with the drawing tools, I took on the challenge of tracing the excellent ambigrams of the four elements that John Langdon designed for the book Angels & Demons. I downloaded the small GIF files from johnlangdon.net, and then used the pen tool in Illustrator to trace the outline. I also had to make lots of small adjustments to add in the details that are absent from the low-res originals. I had to make educated guesses about how these details were supposed to look. Here's the first one, Earth:
This seems like a relatively simple design, but the ea/th combination is not at all an obvious solution. It's clever and very effective.