Used at Bay Mills Community College by our Master Bow Maker Web Kinney to draw a center line down the length of a bow which can vary in thickness and curvature.

Place a pencil down the center. Use a 1/4in. x 20 bolt in the threaded hole to hold the pencil in place. Hold the tool with the two opposite plastic cylinders in constant contact with the sides of the object. This keeps the pencil centered between them at all times.