At first I was just going to create a pattern but at the last minute decided to add runes. The runes are placed in two different locations - both vertically and horizontally - on the design. Wanting to make the second set of runes more subtle than the first, I decided on the green so it would match the background color.
I'm pleased with the way it turned out. But I might add a few color variations. Haven't made a final decision on that as of yet. I'm also tossing around the idea of removing the runes and just leaving the Celtic pattern to add to merchandise as well. But, it's just an idea for right now.
This particular design, Celtic Runes 1, is available on merchandise in my Shadow's Lore store.