Turn a yardstick into a large-circle compass

For a trusty compass that makes it easy to draw circles of many sizes, drill ⁵⁄₆₄ " holes at every ¹⁄₈ " mark in the first inch of a metal yardstick. Now, drill ⁵⁄₆₄ " holes at every inch on the rest of the yardstick's length. This also works fine in a wooden yardstick. Just space the holes ¹⁄₄ " apart in the first inch for strength. To draw a circle with a 27³⁄₄ " radius, for example, tap a 19- or 20-gauge brad through the drilled hole at the ¹⁄₄ " mark. Next, insert a pencil point into the 28" hole (28"¹⁄₄ "=27³⁄₄ ") and draw your circle.
—Walter S. Thomas, Jr., Drexel Hill, Pa.