I don't know of a means to generate or revolve a shape like this. What you could do is add a large diameter silk screen circle on the "entry" side for the countersink. You may be able to create a 2D torus in color to place at the same coordinates. At a glance in 3D, you would have a visible effect at least. Of course, your fab drawing needs to call out the drill / countersink details.
