Hi billis - in this case your surface has an area where it is collapsed down and sort of folds back right back over top of itself in this area here:





That kind of "self intersecting" surface cannot be used for getting a proper offset or shell.

Basically the mechanism of shelling and offsetting tries to create a surface that is moved by a given distance along the base surface's perpendicular/normal direction.

When there is a collapsed folded area like that, it causes the surface normal to wildly flip around all over the place in that area, creating a kind of chaotic zone for the offset.

You'll need to get the base surface to be more cleanly and simply structured for shelling to work, I'll see if I can think of some suggestions for you, possibly you may want to build a larger dome first, and then use something like a boolean to cut a piece out of it rather than trying to build it all in one go with Network.

- Michael