If you have modelled the thickness of the metal you have two faces very near one another that fight for visibility when you orbit. It gets worse if your model is far from the origin, and if the camera is placed weirdly - that can happen when you use Parallel Projection instead of perspective.
Thickness wasn’t modelled (yet), but switching between the two fixed it. Thanks!!
@kenzie ,
FWIW, modeling in SketchUp is best done in perspective. Parallel projection is mostly used to create scenes for output.