A similar device has already been created and tested on the Internet, we will consider its reduced copy, created for marking the ends and narrow strips.
The craft is a small rectangle of steel with bearings mounted on its sides. For convenience, finger recesses are machined on the sides of the plate. In the center of the fixture, holes for a pencil or marker are made.
The centralizer works on the same principle as its large copy, the surface is clamped between the bearings and the center is marked with a pencil in a long line.