Unable to calculate volume

Unable to calculate volume or see the solid section in clipping plane due to the non-manifoldness.
How to deal with it?
What does it even mean in simple English?
non-manifold volumes.3dm (673.6 KB)

Non-manifold means some edges are shared by more than 2 faces, or some faces are connected only via a vertex.

Ok, got it. I can see it. What’s the fix?

Use _ShowEdges to see which edges are naked or non-manifold. You’ll probably have to rebuild some faces to get rid of them.

Strangely, I can only see one edge (I have done some fixing) yet it is still unable to calculate the volume for both, independently.

The other object has naked edges. If you zoom in to this area you can see that the edges aren’t completely aligned.

I can see it now. Blame the fast modeling.