Free 3MF Repair Tool

A 3MF file is a zipped package, not a single mesh. Inside it, your slicer stores each object, where it sits on the plate, the units, and often your print settings. The errors your slicer reports live in the mesh of one or more of those objects. They usually come from a CAD export with loose seams, a scan or AI-generated model with small gaps, or two parts pushed together until their surfaces overlap. Your slicer can often print around small gaps, but it warns you because it can't tell for sure which side of a surface is solid. That doubt shows up as missing walls, odd infill, or layers that stop halfway.

Each object on your plate, and each part inside it, is checked and repaired on its own, so parts that touch are never glued together. It is then written back as its own object in the downloaded file, in the same position. Duplicate points are merged, zero-area triangles are removed, flipped faces are turned the right way, and small holes — up to 32 edges around the rim — are closed automatically. Files saved in inches or centimeters are converted, so the repaired file is always in millimeters. You see the counts before and after, so you know what changed instead of trusting a green check mark.

After a 3MF repair, the download holds clean geometry, not your whole project. Painted colors, filament assignments, and slicer project settings are not kept, and the tool warns you when your file contains them. Modifier and negative parts are left out too, so a cut-out made by a negative part is not applied. If those settings matter, keep your original project: open the repaired 3MF, then copy your settings across or repaint the few areas you need. Large holes are reported rather than patched, because a flat patch over a big gap would change the shape you designed.

Use it when your slicer flags non-manifold edges on a model you downloaded, when a shared project slices with gaps, or when the slicer on your computer has no repair option. It runs in any modern browser on Windows, macOS, Linux, or a Chromebook, with no plugin or sign-up. If your model is a single STL rather than a 3MF project, the STL repair tool gives you the same diagnosis for one mesh.