Manifold versus watertight
Watertight means no open edges. A closed and manifold result also requires no non-manifold edges in the resolved build geometry.
What topology issues mean
Open edges can indicate holes. Non-manifold edges are shared by more than two faces and can make a surface ambiguous to downstream tools.
How build transforms are handled
The checker analyses supported build-item and component transforms, rather than only the first stored object.
What this tool does not verify
It does not check part clearance, overlap, printer configuration, supports or every condition that affects printability.
FAQ
Can a 3MF contain separate parts?
Yes. Separate closed parts are allowed and shown separately.
Does this guarantee a successful print?
No. Use the full quality report and confirm the final setup in your slicer.