"Even by the time I was making smiley faces, I didn't really believe that the method worked as well as it did," Rothemund says.

Rothemund has developed a computer program that can analyze a shape, figure out the right folding pattern, and then tell you what DNA staples you need to make that shape.

But the real goal of this work isn't tiny maps. Rothemund says that in the future, tiny DNA shapes could serve as scaffolds for quickly building nanostructures made of metals or other materials.