I tried everything I know and researched the forum for hours but still cannot find this seemingly simple task in GH .To cap a curved brep.
Curving the fish 1.1 cannot cap.gh (39.9 KB)
As you can see in the image, the top is capped but the bottom which is curved will not cap.
I tried lofting (might have missed the right option)
I tried extruding from the curved bottom
and i tried splitting the flat extrusion with the curved surface.
I tried both versions of cap and cap ex on the last two.
How do you cap a bottom like this?
The purpose is to cnc mill the bottom part but it’s hard to define a 3D shape without it being solid. RhinoCAM didnt like the open curves. 
Thanks very much for your help.