You guys are suggesting workarounds for this prop. I'm not interested in this prop, per se, and workarounds specific to this lid. I'm asking about the hundreds of props I've wasted time with because they have inconsistent normals as defined by the winding order of the polygons. 

Note that the particular suggestion of just covering this lid with a new polygon will lose the modeling that is in the lid. It's engraved, and the corners are nicely rounded so they catch the light like a real object, not some CG idealist box with hard corners. The point of using this box was the modeling - it's superb. Replacing it with some crappy rectangle polygon would defeat the whole purpose.

Similarly, when I find a nice, but unusable car, I'm not going to start slapping flat rectangles on it as a workaround.

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I tried Stomp and Blender - both changed the normals but did not produce a consistent surface after all.

In Blender, rendering with the Blender rendering engine, I see the same artifacts as Poser and OpenGL produce.

However, when I use Cycles renderer it looks fine. Obviously the interpretation of consistent normals was either not performed after all, or was not producing the explicit normals that Cycles was using. Maybe there are internal flaws, like three polygons sharing a single edge. Obviously the prop needs to be a proper manifold in order to have a sensible interpretation as a single surface.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)