If this aids your argument, nearly All video game models that I tried to convert to 3D printing STL files were non-manifold. I think this logically follows fro

If this aids your argument, nearly All video game models that I tried to convert to 3D printing STL files were non-manifold. I think this logically follows from your statement, and it made fixing the stl files necessary otherwise the printer would switch to imaginary coordinates halfway thru the print and since the printer is mechanically restricted the print does a good impression of an Escher painting.