One way to make the crescent-shaped piece would be to glue several wedge-shaped wooden pieces together, so that they form the characteristic curved shape. If only a few wedges are used, then the the shape should be finished with a rasp, files and sandpaper. This method has not been tested, but should work fine, provided that the surfaces of the wedges are perfectly flat so that the glue joints end up being strong.

There are also other ways to make this component that have been tested in practice.