Surface Will not Display in Rendered, Shaded, Arctic, etc

Here is a file with a bit of weirdness. I have a surface that will show in wireframe and the outline ships up in shaded. However, it will not shade nor will it show up in a rendered mode.

Problem Render.3dm (3.5 MB)

If I were to guess the triangles at the bottom of the shape are the problem. If I per triangle explode, delete bottom curve, extend the two remaining ones, trim the outer curve and the legs, rejoin with outer curve then I’m able to create a trimmed surface that also shades.

I don’t know how you trimmed the surfaces, but doing each bit manually was a bit cumbersome. So the quickest way I found was to use ExtrudeCrv with a distance, then extracting one of the surfaces you want (or keep the solid if that is what you’re after eventually anyway).

I’m no surface expert by any means, I’m generally happy when something renders in Raytraced. @pascal probably has some better tips and corrections.

Problem Render one way.3dm (6.6 MB)

Raytraced & Arctic

The bottom curve fixed up