.obj
Assimp
OBJ → STL
Wavefront OBJ
The most common format among modelling tools. Quads are triangulated during conversion, so the mesh comes out closed.
Accepted formats
Ten inputs.
Ten inputs.
One output.
Each format has its own conversion engine. Below, what changes in each one — and why that matters once the file reaches the slicer.
One by one
What changes in each format.
Click to open the format page and convert right there.
.fbx
Assimp
FBX → STL
Autodesk FBX
Comes out of Maya, 3ds Max and Blender. Materials and animation are dropped — STL holds geometry only.
.3mf
In-house engine
3MF → STL
3D Manufacturing Format
Bambu Studio and OrcaSlicer use the “production” extension, keeping geometry in separate files inside the package. We read those files and ignore negative parts, which are slicer cuts.
.ply
Assimp
PLY → STL
Polygon File Format
The usual output of 3D scanners and photogrammetry. Per-vertex colour is dropped, the mesh is preserved.
.dae
Assimp
DAE → STL
COLLADA
An interchange format carrying scene, camera and lights. We extract the meshes only and flatten the transforms.
.glb
Assimp
GLB → STL
glTF binário
The web and modern-Blender standard. Both GLB and glTF are accepted; the node hierarchy is resolved before it becomes STL.
.step
Open CASCADE
STEP → STL
ISO 10303 · STP
Real mechanical CAD, from SolidWorks, Fusion 360, Inventor or FreeCAD. It goes through a full geometric kernel, not a mesh reader.
.iges
Open CASCADE
IGES → STL
IGES · IGS
The older CAD interchange standard, still common with industrial suppliers. Surfaces are tessellated by the same kernel used for STEP.
.dwg
LibreDWG
DWG → STL
AutoCAD Drawing
AutoCAD's format. We convert what is already 3D in the file: meshes, 3D faces and flat-faced solids. A 2D drawing has no volume and curved-surface solids cannot be read yet — in those cases we tell you right away, and the way out is exporting STL or STEP from AutoCAD itself.
.dxf
LibreDWG
DXF → STL
Drawing Exchange Format
The open counterpart of DWG, exported by AutoCAD, SketchUp, Revit and nearly every CAD tool. Same rule: meshes, 3D faces and flat-faced solids become STL; the drawing unit (mm, cm, m, inch) is converted to millimetres.
Under the hood
Four engines, not one.
Mesh
Assimp — OBJ, FBX, PLY, DAE and GLB/glTF. Triangulation is forced on export: without it, four-sided faces lost half their geometry and the STL came out with holes.
3MF
In-house engine — reads the “production” extension from Bambu Studio and OrcaSlicer, resolves references between inner files, composes the transform matrices and discards the negative parts.
CAD
Open CASCADE — STEP and IGES. A full geometric kernel, the same kind used inside CAD programs. It is what lets a SolidWorks or Fusion 360 file convert without turning into triangle soup.
DWG
LibreDWG + ezdxf — DWG and DXF. The DWG becomes DXF and we take what is already 3D: meshes, 3D faces and flat-faced solids, in the right unit. 2D drawings and curved solids are refused with an explanation, instead of producing an empty or distorted STL.
Output
Binary STL, validated: if the generated file has no triangle inside, the conversion fails with a clear message instead of handing over an empty download.
From file to part in hand.
Converting is the easy part. The hard part is finding someone who prints it right, charges a clear price and delivers on time. So we recommend exactly one — the one we use.
Disclosure: we have a commercial partnership with NEO 3D Print and are paid for referrals. That is what pays the server and keeps the tools free, with no sign-up and no third-party ads. We recommend them because they are who we use — and the text above describes their service, not an independent review.