Hi Steve, so the deal here is that your outer curve is not quite as it seems - it has an extra segment in it that makes it loop around on top of itself.

If you look at this area here closely you can kind of see it's a bit darker:



Then if you use Edit > Separate to break it apart into segments and move this segment over, that will help you to see the extra portion where it was wrapping around on top of itself:



So you'd need to clear that up in order to do a network with it.

But also you're going to have some difficulty trying to build a network with curves like this which have such significant differences between their shapes. You'll get a lot of pinching and bunching type effects trying to collide such different shapes together into a single surface like this.

So for example the curve you have here:



Is very very different in it's overall shape than the other on the other side here:



Trying to build a single surface is going to try to force the surface to incorporate each of those very different shapes being blended together, you're not going to get a good result with that type of stuff.

Also contributing to the problem are the sharp corners in some areas, like here:



Those sharp corners will kind of make sharp areas that sort of radiate out from them as the sharp-cornered curve is being blended with the other curves in order to build a surface - Network involves a sort of blending together of the shapes involved to build a surface.


So instead of trying to build something like this all out of 1 network surface, you would probably want to make a more simplified larger sheet and then trim away some spots with side profile cutting curves to make sharp cutouts and stuff like that, rather than trying to build a cutout directly into the initial surface itself.

I'll try to make an illustration.

- Michael