I still think the 3D Rail Revolve method might be an easier way to do this shape.

In the attached file I Rail Revolved the two green lines to create the wavy surface and reshaped it with an Extruded & truncated ellipse, which I slightly shrank to get a clean Boolean. It seems like a fair start to me.

If you show the control points of the rail curves, then MoI's history feature means it's possible to make some nice tweaks to the resultant surface to get it how you want it.


Martin.