Why are Carpenter's pencils square?

Two reasons. The square shape enables carpenters to draw thin or thick lines more easily than with conventional pencils.
But a more pressing point: If we drop a pencil from our desk, it would not be a big deal to lean over and pick it up from the floor. However, what if we happen to drop a pencil from a beam on the thirty-fourth floor of a construction site? Or the roof of a home? To put it simply, Carpenters' pencils are produced in a square shape so they won't roll of building materials.
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