Art -

I was able to get a nice Shell result by restructuring the Network:

1. Select the two black curves and Join into a single curve.

2. In top view, split the blue and green curves in half where they cross each other. I used Trim points for that. Make sure the curves touch at a single point. Make sure the curves touch the joined black curve.

3. Optionally you can place a small circle where the 4 curves meet at the top. This can help smooth the Network where the points converge.

4. Select all curves and Network. Shell the result.

Sometimes you get pinching with a Network and the Shell amplified that pinching. When that happens I try other Network structures.

Ed Ferguson