Wooden Marking Gauge with a Wedge-Locked Headstock

A marking gauge scribes a line parallel to an edge: a square beam slides through a headstock, a steel pin near the end of the beam scratches the line, and a wedge locks the headstock at the distance you set. Make it from a hardwood strip and a filed steel pin. The picture: a small walnut marking gauge; this one locks with a brass screw and marks with a blade, where ours uses a wedge and a pin.