Which CAD Files Can You Upload? STEP, STL, 3MF, SolidWorks and More
Which file formats get an instant 3D printing price, which an engineer quotes by hand, and what to send when you only have SolidWorks, Rhino or a drawing.
The Short Answer
Five formats get an instant price on our quote page: STL, OBJ, 3MF, STEP (.step or .stp) and IGES (.iges or .igs). Native files from SolidWorks, CATIA, Inventor, Parasolid, Rhino and SketchUp, and DXF, JT, SAT, PRT, PLY, 3DS and DAE files, are quoted by an applications engineer, usually the same business day. Email those to hello@3dservicesusa.com.
The Five Instant-Quote Formats
| Format | What it stores | Best for |
|---|---|---|
| STEP | Exact solid geometry and its unit | Anything from parametric CAD. The best default. |
| 3MF | Mesh, unit, and every object in a project | Slicer projects and mesh workflows where units matter |
| STL | Triangle mesh only, no unit | Universal. Fine when exported fine enough and in millimeters |
| OBJ | Mesh, sometimes color, no unit | Sculpting and scanning tools |
| IGES | Exact surfaces from older CAD | Legacy systems. Send STEP when you can |
Why STEP Is the Best Default
STEP carries the exact solid, so nobody has to decide how finely to approximate your curves, and it carries its unit, so the size cannot be misread. We measure it accurately too. On 45 real customer uploads measured in October 2026, the volume we computed from STEP files was within 0.26% of the exact solid in the worst case, and within 0.08% on average. For STL and 3MF, our measurements of volume, surface area and bounding box matched two independent geometry libraries to about one part in 100 trillion.
3MF From a Slicer
Project files saved from desktop slicers are read whole, including objects that the slicer stores in separate model files inside the package, each in the position and orientation you placed it, and in the unit the project declares. If one project holds several different parts that you want priced and counted separately, export each part as its own file before you upload.
Native CAD: Send It, We'll Quote It
You don't need to convert a native file to get a price. Email it and an applications engineer opens it and quotes it, usually the same business day. These are the formats we accept that way:
- SolidWorks: SLDPRT, SLDASM
- CATIA: CATPART, CATPRODUCT
- Inventor: IPT, IAM
- Parasolid: X_T
- Rhino: 3DM
- SketchUp: SKP
- Interchange and mesh formats: DXF, JT, SAT, PRT, PLY, 3DS, DAE
Drawings, Photos and PDFs
ZIP, RAR, PDF, JPG and PNG files can go with a quote request as supporting documents, such as a drawing with tolerances or a photo of the part in use. They are not geometry, so they cannot be priced on their own. If a drawing is all you have, our AI CAD tool reads a dimensioned drawing, sketch or photo (PNG, JPG, WebP or PDF), shows you every dimension it read and where it read it, and builds STEP, STL and 3MF once you confirm them. Today it builds flat rectangular plates automatically, optionally with four through-holes and rounded corners. Other parts are held for a person to quote, never approximated.
When an Upload Is Refused
We check that a file really is what its name says before we try to measure it. A .step file must begin with the standard STEP header, and a .3mf file must be a ZIP package, as every 3MF is. The most common surprise is an email attachment on an iPhone that was never downloaded: the file picker hands over a tiny stand-in with the right name and none of the geometry. Open the attachment in Mail, or save it to Files, then upload it again.
What to Send
- Designed in parametric CAD: export STEP.
- Working in inches: STEP or 3MF, so the unit travels with the file.
- Only have a mesh: STL in millimeters, or 3MF.
- Only have a native file: email it, or export STEP for an instant price.
- Only have a drawing or a photo: try AI CAD, or send it with your quote request.
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