Group of Networked Surfaces not capping

I am just starting out with Rhino. Attached is a file where I am trying to create a close solid from several networked curves. I can get all of them to join and then cap the bottom of the model, but the top of the model just will not cap. It says that the openings to not have closed planar loops of edges, but I cannot find a way to properly fix this. Does anyone know what I need to be doing?

The file includes the curves from which I networked the surfaces as well.

Bass Body Contour Attempt.3dm (133.3 KB)

Thanks!

Hi Nick - I would make the full body first then a surface for the cut and trim that in to the body. As is, the curves you have defining the cutout are a little sparse - hard to say what you want to happen there but I would make this surface extend past the body on all sides- think if it as a cutting tool - and when the shape is right, trim it in. You can get an idea of what I mean by-

  • Extrude the full curve for the body to the full thickness, making a closed solid.
  • Select the curves that define the cut and run Patch, with Automatic trim uncheked. The shape will not be quite right but you’ll get the idea
  • BooleanDifference the surface from the solid.

-Pascal