Model has incomplete sides from a certain view

[YamadaRikkuDev (saykets)]

When I try to export my speaker box model, it would show up as light gray, and some sides behind it are not seen unless you turn around the camera.

Here is what I want it to look:

I know certainly why it looked gray because I haven’t baked the materials in Blender yet. But I am not too sure about why some vertices would look incomplete.

This is my first time modeling, I am not sure why I stumbled upon this problem.

Any solutions are welcome.

[GamEditoPro]

Select all vertex, and recalculate normals outside (Shift+N)

[YamadaRikkuDev (saykets)]

Excellent! I should consider normals as well.