File requirements

The uploader accepts four formats: STL, OBJ, 3MF, and STEP. Acceptance at upload and success at analysis are separate matters. Only STL and 3MF complete the pipeline reliably. OBJ and STEP are accepted and checked, but typically error once the slicer attempts to load them.

PrintPort3D validates the contents of your file, not only its name. Renaming a STEP file to .stl does not work: the upload is rejected with “Model file contents do not match the declared file type.” Export in the format you intend to use.

Two separate size caps apply, depending on where you upload from.

Seller upload500 MB

Your Files accepts files up to 500 MB. Anything larger is refused the moment you select it, with “File is too large (max 500MB).”

Public instant quote25 MB

The free, no-login quote calculator on the marketing site uses a smaller 25 MB cap. It is a preview tool. The full 500 MB limit applies once you are signed in and uploading to your library.

Most well-made STL and 3MF files fall well under 500 MB. A very large file usually indicates an extremely high triangle count. Decimating the mesh in your tool reduces the file size and upload time without changing the printed result.

After upload, analysis measures the model’s bounding box and volume. Three checks are hard rejects. Crossing any one marks the design as Failed in your library, with the reason shown on the row. These are the only geometry rules that stop a design.

The smallest-side check catches an entire model that is too small, such as a coin exported at 0.3 mm thick. It is not a per-feature rule about tiny details, and it is a fatal reject rather than a warning. When a model designed at a sensible size is rejected as too small, the cause is almost always units. See the next section.

Knowing what does not block an upload matters as much as knowing what does. Two concerns sellers often raise are never enforced.

• Watertight or manifold geometry is not required. A mesh with holes or non-manifold edges is logged but still slices. Analysis neither warns you nor stops the upload. Clean geometry still prints better, so it is worth fixing in your tool even though PrintPort3D does not gate on it.
• Wall thickness is never measured. There is no minimum-wall check anywhere in the pipeline. Thin walls affect real-world print strength, but nothing in analysis flags them.

The only geometry PrintPort3D repairs automatically is inverted normals. An inside-out mesh is flipped and processing continues. Holes, gaps, and non-manifold edges are noted but not repaired. The analyzer measures far more than it fixes, so do not rely on it to clean up a rough mesh.

A few habits in your CAD or mesh tool prevent almost every rejection.

1. 1

   Model in millimeters at true size

   PrintPort3D reads your coordinates as millimeters, as-is. Export at the real physical size you want printed. A model built in inches or centimeters arrives tiny or enormous and can trip the size checks.
2. 2

   Confirm the 3MF unit setting

   The 3MF unit setting is a common source of error. The reader ignores the unit declared inside a 3MF and uses the raw coordinates, so a 3MF exported in inches or meters is silently mis-scaled and may then fail the too-large or too-small check. Author 3MF files in millimeters. If you are unsure, export STL instead.
3. 3

   Keep the longest side at or under 255 mm

   Check your model’s bounding box before exporting. If any axis exceeds 255 mm, scale it down or split it into printable pieces.
4. 4

   Export a solid, closed mesh

   Export a real 3D solid, not a flat surface or an empty shell. This keeps you clear of the zero-volume reject. Sitting the model square to the axes rather than tilted also keeps the measured size matching what you designed.
5. 5

   Save as STL or 3MF

   Finish on one of the two reliable formats. This single step avoids the OBJ and STEP analysis failures entirely.

A failed design shows a red Failed dot and the exact error on its row. The message identifies what to change. The common ones are explained below.

The fix is always a re-upload, not an edit. Correct the file in your tool and upload it again. If a message does not match anything here, or a file you are confident is clean keeps failing, work through Troubleshooting or use Get help with this to reach support.