I've had the experience of laying out driveways using old fashioned optical surveying equipment and it's not easy to do this in the daylight. I suppose with GPS and computerized equipment that it's an easier job nowadays. I think it would be a difficult job to establish the relative location of the centers of circles and endpoints of lines at night. It's certainly not impossible to do it with strings, but if you've ever done such work in daytime, you realize how much tramping around it takes. It's much more efficient to have an device like a transit that can accurately measure angles.

Saying that people create crop circles with boards and strings is like saying that people build automobile engines with metal and grinders. It could be true, but it doesn't really explain how it's done. The boards-and-strings theory needs elaboration. One possibility is that the layout is done with GPS and other modern technology. Another possibility is that that certain landmark points are put down days before the crop circle is completed, so the work goes quickly. Another possibility is that the design of the circle incorporates certain nice geometric coincidences that makes laying it out easy.

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