STL → 3MF
Open the model in a compatible tool and save as 3MF. You can add units, placement, and project settings, but the existing triangle mesh does not become smoother or regain CAD history.
← Learning library3D printing file formats: From a file
3D printing file formats: From a file
to a finished part.
STL, 3MF, STEP, and everything in between. Understand what each file carries, what it leaves behind, and where it belongs in your workflow.
01 / Follow the file
Three stages. Different jobs.
- 01 · Design
Keep an editable original
Native CAD or modeling files preserve the working design. STEP helps exchange CAD geometry.
- 02 · Prepare
Bring the shape into a slicer
STL, 3MF, and OBJ carry model geometry. A slicer project can also preserve placement and print settings.
- 03 · Print
Export for your machine
The slicer produces compatible G-code or a resin job file using your printer and material settings.
02 / The reference shelf
Know what you’re opening.
Select a format to see its uses and limitations. Support depends on the application and printer.
.stlSTLMesh
A surface made from triangles. Binary and ASCII versions describe the same kind of geometry.
Use it to
Share a simple shape with broad slicer support.
Before you continue
No standard units, color, materials, or slicer settings. Check imported dimensions; coarse triangles can show on curved surfaces.
.3mf3MFPrint exchange / project
A package containing meshes, explicit units, object placement, and potentially materials or color.
Use it to
Save a print project or exchange multiple parts together.
Before you continue
A model-only 3MF and a slicer project are different uses of the same container. Printer profiles, supports, and other application-specific settings may not transfer between slicers.
.obj + .mtlOBJMesh
Polygon geometry with optional texture coordinates and companion material and image files.
Use it to
Move sculpted or textured models between creative applications.
Before you continue
Keep companion files together. A slicer may import only geometry and ignore textures or material definitions.
.step / .stpSTEPCAD exchange
CAD exchange data that can preserve precise surfaces, solid bodies, assemblies, and units.
Use it to
Pass mechanical parts between CAD tools for further editing.
Before you continue
Usually does not preserve the original parametric feature history. Slicers that accept STEP may convert surfaces into triangles on import.
.iges / .igsIGESCAD exchange
An older engineering exchange format for curves, surfaces, and other geometric entities.
Use it to
Exchange legacy CAD geometry when STEP is unavailable.
Before you continue
Imported surfaces may need stitching into a closed solid. Convert through CAD software before slicing if your slicer does not support it.
.amfAMFPrint exchange
An XML-based additive manufacturing format with units and support for materials, colors, and multiple objects.
Use it to
Exchange manufacturing data in workflows that explicitly support AMF.
Before you continue
Support is less widespread than STL or 3MF. Confirm which features the receiving application retains.
.plyPLYScan / mesh
Vertices and optional faces, often with per-vertex color or other scan properties.
Use it to
Transfer scanned meshes or point-cloud data for cleanup.
Before you continue
A point cloud is not a closed printable surface. Reconstruct and repair a mesh first; color import depends on the application.
.f3d / .FCStd / .blend / .3dmNative design filesEditable source
The design application’s working document, which may retain sketches, constraints, features, modifiers, or scenes.
Use it to
Keep the master copy for future design changes.
Before you continue
Capabilities differ by application. Export a supported mesh or exchange file for the next tool and retain the original.
.gcode / .gco / .gcG-codePrinter instructions
Commands for machine motion, extrusion, temperatures, and other supported printer actions.
Use it to
Run a filament print after slicing for the intended machine.
Before you continue
Printer dimensions, firmware dialect, nozzle, material, and start/end commands matter. Re-slice the source model when moving to another printer.
.bgcodeBinary G-codePrinter instructions
A binary container for G-code data, with optional compression and metadata.
Use it to
Reduce job-file size in a compatible slicer and printer workflow.
Before you continue
Requires explicit firmware support. Renaming a text G-code file does not convert it into binary G-code.
.ctb / .goo / .photon and othersResin job filesPrinter instructions
Printer-specific sliced layers plus exposure, lift, and other job settings.
Use it to
Run a resin print prepared with a matching printer profile.
Before you continue
File extension alone does not guarantee compatibility: format version, screen resolution, printer model, and firmware can matter.
.svg / .dxfSVG and DXF2D starting geometry
Vector paths or CAD drawing entities used as an input to modeling.
Use it to
Turn a logo, outline, or drawing into an extruded part.
Before you continue
They are not generally a ready-to-print 3D solid. Close profiles, set scale, and add thickness in a supported tool.
03 / The everyday choice
STL or 3MF?
| Information | STL | 3MF |
|---|---|---|
| Shape | Triangle mesh | Triangle mesh; additional capabilities through extensions |
| Units | Not standardized in the file | Explicit units |
| Multiple parts | Disconnected shells, without rich object structure | Separate objects and their placement |
| Color and materials | Not part of standard STL | Supported; application and extension dependent |
| Slicer settings | Not included | May be saved by the slicer; not universally portable |
| Original CAD history | Not included | Not restored by saving as 3MF |
For repeatable work: keep your native design, save a slicer project, and export a job for the intended printer. A 3MF extension alone does not mean the file is ready to print.
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04 / Make the handoff work
Conversion changes the container.
It cannot recover missing detail.
3MF → STL
Export the required objects as STL. Expect to lose units metadata, color, material assignments, and project settings. Check whether the export combines parts or writes separate files.
STEP → STL or 3MF
Export from CAD or import into a supporting slicer. Choose mesh resolution appropriate to the part: coarse export can visibly facet curves; unnecessarily fine meshes increase file size.
STL → STEP
Mesh-to-CAD tools may wrap facets or reconstruct surfaces. Saving a STEP file does not automatically recover a clean parametric model. For substantial changes, obtain the original CAD file.
Why is the model the wrong size?
Check the expected dimensions and import units. STL does not standardize units; an inch/millimeter mismatch produces a 25.4× scale difference. Verify dimensions before slicing.
Why does the model have holes or disappear in the slicer?
Inspect for open edges, inverted faces, self-intersections, and zero-thickness surfaces. Repair the geometry, then inspect the layer preview; a successful import alone does not prove printability.
Can I reuse someone else’s print-ready file?
Only with a compatible machine and appropriate settings. Prefer the model or project and re-slice for your printer, nozzle, material, or resin. A matching filename extension is not sufficient.
Go to the source
Specifications & further reading
- 3MF Consortium — core specification and extensions
- PrusaSlicer — supported file formats and import behavior
- Prusa Research — binary G-code format
- Library of Congress — STL format description
Continue with the software directory or return to the learning library.