Girih tiles are an ancient Islamic art form which have some interesting mathematical properties. Like Penrose tiles, they will tile an infinite plane without any repeating pattern. They also have the same five-fold, quasicrystal properties, although they were in use hundreds of years before Roger Penrose's discovery.
In Islamic architecture, the edges of the tiles are traditionally not emphasized. Instead, the lines you can see on the interior of the tile are highlighted in a contrasting color. When the tiles are arranged, these lines form intricate knot-work patterns.
I printed these on a Form 2 in Grey V4. I highlighted the lines by painting them with Rustoleum enamel paint.