There is a method that can be done on a lathe-like device. Of course, this is what I think for you. I've never done it. When the wood is cut into a nearly circular shape, it goes on the lathe, with bowl-shaped clips at both ends against the workpiece and hands against the semicircular knife used by the engraving machine. For a larger circle, a semi-circular knife is used to change the direction of the workpiece from time to time, and then a caliper is used to measure it, and finally a bead very close to the standard circle can be obtained. It is best to use copper for the fixture of jacking beads, with a dead top in the direction of chuck and a convertible top in the direction of tailstock. The principle is as follows, but the top surface should be changed to a plane.