Free online 3DM to 3MF converter

A slicer, printer workflow, or manufacturing application may accept .3mf but not Rhino’s native .3dm format. Converting the file exports editable NURBS geometry as a triangle mesh, so tessellation settings determine dimensional accuracy and surface quality.

What the 3DM format is

3DM is the native file format of Rhinoceros (Rhino), a CAD and 3D modeling application developed by Robert McNeel & Associates. It stores NURBS curves and surfaces, polygon meshes, solids, layers, object attributes, blocks, materials, annotations, and other Rhino-specific data.

Rhino users in industrial design, architecture, jewelry, engineering, product development, and general 3D modeling commonly exchange 3DM files. The format is intended to preserve an editable modeling document; it is not primarily a 3D-printing delivery format.

What the 3MF format is

3MF (3D Manufacturing Format) is an open specification maintained by the 3MF Consortium. A 3MF file is a ZIP-based package containing XML model data and, when supported, thumbnails, textures, materials, colors, relationships, and production metadata.

Its model data consists of triangle meshes rather than editable NURBS surfaces. Compared with STL, 3MF can store multiple objects, object relationships, color and material information, and unit metadata in one package. Support for these features varies among slicers, printers, and CAD applications.

How to convert 3DM to 3MF

Using Rhino

1. Open the .3dm file in Rhino.
2. Confirm the document units under File → Properties → Units. Check the model for naked edges, self-intersections, duplicate faces, and non-manifold areas before exporting.
3. To export the complete model, use File → Export as appropriate for the Rhino version, or select the required objects and use File → Export Selected.
4. Choose 3MF (*.3mf) in the file-type list and save the output file.
5. When Rhino opens mesh or 3MF export settings, choose a tessellation fine enough to represent curved surfaces, holes, thin walls, and small features. Use custom mesh settings for dimension-critical parts rather than relying only on a visual preset.
6. Open the resulting .3mf file in the target slicer or manufacturing application. Verify a known dimension, object placement, surface appearance, object separation, and repair warnings before production.

Rhino is usually the most direct desktop option because it reads the original 3DM data and controls conversion from NURBS geometry to a mesh. Menu names and available export settings differ between Rhino releases.

Converting without installed software

You can convert the file for free on 101convert.com without installing software. Upload the .3dm file, select 3MF as the output format, start the conversion, and download the resulting .3mf file. Verify the result in the intended slicer, especially when the source contains precise dimensions, separate objects, colors, or materials.

Quality and compatibility limitations

• NURBS geometry is tessellated: the 3MF file contains triangles, not Rhino’s original editable curves and surfaces. The exported file cannot reconstruct the original NURBS model.
• Tessellation affects accuracy: coarse settings can create faceted cylinders, distorted silhouettes, or undersized holes. Excessively fine settings increase file size and can slow import or slicing. Inspect curved surfaces and critical dimensions after export.
• Rhino-specific data does not become editable 3MF data: command history, parametric relationships, construction geometry, many annotations, and Rhino rendering settings generally do not transfer.
• Printable solids need valid boundaries: repair naked edges, open surfaces, duplicate faces, self-intersections, and non-manifold geometry before slicing. A visually closed model can still contain mesh defects.
• Check units in the destination application: 3MF supports unit metadata, but an importer can interpret dimensions incorrectly. Compare a known Rhino measurement with the value reported by the slicer.
• Appearance transfer is limited: basic colors may transfer, but Rhino render materials, procedural textures, and advanced shaders usually do not become equivalent 3MF material data.
• Application support is uneven: a program may open the 3MF package while ignoring textures, colors, production data, or multiple-object relationships. Confirm which 3MF features the target workflow supports.