Unique, or one of the Seven Basic Plots? An author I know who writes fantasy fiction worries perpetually about whether her plots and characters are original or clichéd. Well, it's hard to come up with a wholly new device or deep structure, but a delight to think how material can be worked and reworked and still exhilarate. In this case, one shape is used repeatedly in a tile design that never quite repeats itself. Explore the hat and think about just what satisfies the most—fundamental repetition or endless surface variation.