@kbob@smellsofbikes I don't think they have the same shape; they are curved to create different conic sections as far as I can tell intuitively. I haven't tried to math it or model it though, so feel free to show why I'm wrong.
To model it, I would create the four dovetail surfaces, and then find the intersections with the plane defined by the axis of rotation and the opposite corner.
To math it, I would ask someone else better than me at that sort of thing to do it for me. 💃