I’ve a valid closed polysurface. No naked edges. No non-manifold edges. No bad surfaces.
I uploaded the model (in .stl) to a 3D printing website and it says that the object is incorrect, contains errors and can’t be printed…
I did export before from Rhino to .stl file and uploaded to the same website and my objects were accepted without error. The object is in fact the same object which I made some changes.
Here two screenshots of the check in Rhino before export to .stl and the check result from the .stl file from the website.
Is the problem before the export or is it the export itself. How do I fix it? Thank you for your help.