Keep STEP files beside the printable mesh

An STL is enough to reprint a part. It is a poor source for changing a hole, moving a mounting point, or repairing the original design. When a STEP or STP file is available, keep it with the printable mesh instead of leaving it in a separate project folder.

PrintStash stores both on the same model record. The CAD source, exported mesh, sliced revisions, and print results remain discoverable together.

What the browser preview does

STEP geometry is not made of the triangles a browser viewer expects. On a server running the full image, PrintStash uses OpenCASCADE to tessellate the CAD file into display geometry. That generated mesh powers the model viewer and thumbnail.

The conversion is only for display. PrintStash retains the original STEP or STP bytes for download, and content-hash duplicate detection applies to the source file as it does to other formats.

This used to be an amd64-only feature. Through v0.11.4 the OpenCASCADE dependency had no linux/arm64 wheel, so STEP files uploaded and stored on a Pi or ARM NAS without ever getting a preview. Cascadio 0.1.1 ships wheels for both architectures and v0.12.0 uses it, so the full image now tessellates STEP on ARM as well, verified in CI against an ARM64 image under QEMU rather than on physical hardware. The printstash-api-lite image is the variant that has no STEP tessellation at all, on any architecture.

A useful model layout

For a part you designed, keep these files together:

• the STEP or STP source that can be edited in CAD;
• the STL or 3MF export used by the slicer;
• each G-code revision worth keeping;
• a note explaining any non-obvious design or slicing choice.

Revision outcomes belong to the G-code files. A successful slice can be marked known good, while the CAD and mesh remain source artifacts for the model.

For a downloaded design, import the CAD source when the creator publishes it. A STEP file is especially useful for brackets, enclosures, adapters, and jigs that are likely to need dimensional changes later.

Preview limits are not validation

The browser view is a convenient way to identify and inspect the part. It is not a CAD repair tool and does not prove that an assembly, tolerance, or exported mesh is correct. Open the original in FreeCAD, Fusion, SolidWorks, or another CAD package before making engineering decisions.

Likewise, a model can be stored successfully even when preview generation is skipped because of architecture or memory limits. Treat the preview as an index aid and the original file as the source.

See running on Raspberry Pi or ARM NAS for the ARM tradeoff, or organizing STL, 3MF, and G-code files for the wider file layout.