Free converter · runs in your browser
Turn Bambu Studio, Orca Slicer and PrusaSlicer 3MF projects into clean STL files. Pick the objects you need and export them together or one by one. Your file never leaves your device.
Release to open the file
How it works
Drag a .3mf project from Bambu Studio, Orca Slicer, PrusaSlicer, Cura or a model download onto the converter, or click to choose it. Nothing is uploaded.
Every object and part is listed with its filament colour. Untick what you don't need; modifiers and negative volumes are already left out.
Export one STL, one per object or one per part (as a ZIP). Binary STL is the smallest; choose ASCII only if an older tool needs it.
Actual sample project
The bundled 3MF sample contains a two-part gear, a calibration cube and an infill modifier. The converter shows the real object list, part colors, mesh statistics and export options before you download.
Common uses
Convert 3MF to STL when you need model surfaces without the slicer project. The result is easier to exchange with geometry tools, but units, colours and print settings need separate handling.
Mesh editors and CAD tools often accept STL even when they cannot open a slicer project. Convert the project to repair a boundary, remix a downloaded model, or use the shape as a reference. The result is triangle geometry, not a parametric CAD history.
STL is useful when the recipient does not use Bambu Studio, Orca or another slicer. The converted file contains just the triangles needed by most 3D tools. Tell the recipient the unit is millimetres, because STL does not record it.
Downloaded projects may contain several models or plates. Select only the object you need instead of rebuilding the layout. The 3MF to STL converter can save that selection as one mesh or export every object separately.
STL cannot carry filament assignments, but a colour-painted project is still useful. Export one STL per part so each colour remains a separate mesh. You can then assign filaments in your slicer and align the parts using their shared project coordinates.
Why this converter
A 3MF saved by a slicer is a project: several files, assemblies, helper volumes and settings. STL Kit reads it the way your slicer does.
The conversion runs entirely in your browser. Files are never uploaded, so client parts and unreleased designs stay on your device.
Multi-part assemblies, objects stored in separate model files and multi-plate projects are all read and placed where your slicer put them.
Modifiers, negative volumes and support blockers change slicer settings, not the print. They're left out of the STL unless you tick them.
STL has no colour. Export one STL per part and each filament colour becomes its own file, ready to recombine in another slicer.
3MF units (micron, mm, cm, inch) are converted to millimetres, and the rotation, mirroring and positions from the project are applied.
See the triangle count, volume, surface area and whether each part is watertight before you download.
3MF vs STL
STL stores only triangles. Everything else in a 3MF project is dropped, which is exactly why STL opens in every 3D tool.
| Stored in the file | 3MF | STL |
|---|---|---|
| Triangle mesh geometry | ||
| Units | Declared (mm, inch…) | None, mm assumed |
| Several named objects | One mesh per file | |
| Colours and materials | ||
| Print settings and plates | ||
| Opens in every slicer and CAD app | Most current slicers | |
| File size | Small (zip compressed) | Larger |
Troubleshooting
Most 3MF to STL issues come from project data that STL cannot represent, rather than broken geometry. Check the object list, dimensions and export mode before slicing the downloaded file.
Modifiers, negative volumes and support blockers are excluded by default because they control slicing rather than form the model. Review the object list on every plate. Tick a helper volume only when you intentionally want its shape in the 3MF to STL output.
STL Kit reads the units declared by 3MF and writes millimetres. If the size still differs, check the source project's scale and the destination tool's import units. Do not apply a second inch-to-millimetre conversion to an STL that is already in millimetres.
This is a format limitation, not a failed conversion. STL has no standard colour or material fields. Export per part and keep the original 3MF as the reference for filament assignments. Textures and UV maps are likewise not carried into an STL mesh.
STL is geometry only. Even when a sliced 3MF contains G-code, the converter reads the model and ignores machine instructions. Slice the STL again with your own printer, material, quality and support settings instead of using settings made for another machine.
Other ways
If the slicer is already open, you can export STL there. Use STL Kit when you don't have the app, or want per-object files quickly.
Open the project and select the objects or plates you need. Use File → Export, then choose one combined STL or separate STLs when that option is available. Combined export is convenient for an assembly; separate files work better for individual editing or colour assignments.
Open the 3MF and choose File → Export → Export Plate as STL. Everything on the current plate is saved as one STL, so switch plates or remove unwanted objects first. For separate parts, use the object list and export options in your installed version.
Downloaded a 3MF from MakerWorld or Printables for a different printer? Drop it into the converter above. There's nothing to install. You can inspect every plate, exclude helper volumes and save selected objects without changing the original project.
Menu names and export options vary by slicer version. See the current Bambu Studio documentation, OrcaSlicer project, and PrusaSlicer guides.
FAQ
Yes. There's no sign-up, no watermark and no daily limit. Files up to 100 MB are supported; the real limit is your device's memory.
No. The 3MF is unpacked and converted inside your browser tab. Nothing is sent to a server, so it's safe for confidential parts, and it keeps working offline once the page has loaded.
Yes. STL Kit reads Bambu Studio and Orca projects, including objects stored in separate model files, part names, filament colours and plates. PrusaSlicer and Cura 3MF files work too.
No. The STL format can't store colour or material. To keep a multicolour model usable, export one STL per part; each file then matches one filament.
Those are modifiers, negative volumes or support blockers. Slicers use them to change settings in a region; they aren't part of the printed shape, so they're left out of the STL unless you tick them.
Yes. Untick the objects you don't need, or choose Per object to download every object as its own STL in a ZIP file.
Binary. Both hold the same triangles, but binary STL is about five times smaller and is what slicers expect. ASCII STL is plain text, useful only for a few older tools.
Yes. 3MF files declare their unit, and STL Kit converts everything to millimetres, the unit slicers assume for STL. Rotation, mirroring and scaling set in the project are applied too.
Yes. Use the STL Converter on the home page: drop an STL and download it as 3MF, OBJ or STL.
Yes. Drop the file into the converter above and download the selected objects as STL. Everything runs in your browser, so there is no software to install and no account to create. You can also open the sample project first to see how object selection works.