Open SolidCraft above, model a part, then use File → Export STL… or Export 3MF… to get it into your slicer. This page covers the whole printing hand-off in SolidCraft, the free open-source parametric CAD app, using only what the official docs say. Release checked: v0.18.1, published 2026-10-20 (as of 2026-10-21). New here? Start with the SolidCraft tutorial or the home page.
Why SolidCraft fits 3D printing
Most printed parts are simple solids with a few holes, fillets and a shell, exactly the kind of modelling SolidCraft is built around. The README's own demo is a Raspberry Pi 4 case: a dimensioned sketch, extrude, fillets and shell, standoffs patterned on the board's mounting holes, port cut-outs, vent slots, engraved text, a PETG material with its mass shown in Properties, and a height change made through Parameters.
Three things make it practical for printing:
- It models in millimetres. Imports in metres (glTF) are scaled to millimetres on the way in, and DXF drawings are written in millimetres, so what you type is what the slicer gets.
- It is parametric. Change a wall thickness or a hole diameter in Parameters and the whole timeline rebuilds. That is how you re-export a part after the first test print.
- It exports the two formats slicers want: STL and 3MF, from the desktop app, the browser app and the CLI.
How to export STL or 3MF
The docs give three ways to open the same export dialog:
- File → Export STL… or File → Export 3MF… in the menu.
- Modify → Save as mesh on the Mesh tab.
- Right-click a body and choose the export entry in its menu.
The dialog saves the selected bodies as STL, 3MF or 3MF with face tags, and you can change the format inside the dialog whichever entry you started from. STL is written in binary or ASCII form, according to the capabilities list.
Send to slicer
Tick Send to slicer and SolidCraft writes the file to a temporary folder and opens it in the slicer you pick, instead of asking for a file name. The list shows the slicers found on your computer with their icons. Custom… adds any other program to the top of the list; the entry is kept between runs, and hovering an entry you added and pressing Delete removes it.
This is the fastest loop for test prints: change a parameter, export, and the part is already sitting in the slicer.
In the browser version
The web app at solidcraft.io/app runs the same commands. Exports such as STL and 3MF are downloaded by the browser, so you pick them up from your downloads folder and open them in the slicer yourself.
From the CLI
The headless solidcraft-cli can run a command script, measure a part (volume, area, centre of mass) and export it. Scripts and the MCP server use file.export or file.save_mesh with the format you want, which is handy if you generate a family of parts from one recipe.
What 3MF adds over STL
STL is a bare mesh. 3MF carries a little more, and SolidCraft fills in the parts it can:
| Design property | Where it lands in the 3MF |
|---|---|
| Project | Title |
| Author | Designer |
| Description | Description |
| Licence | LicenseTerms |
You set these once in File → Design Properties… (also under Document Settings in the Browser). STEP and IGES exports get the author and organization too, but STL has no place for any of it.
3MF with face tags is the third option in the dialog (format: "3mf-tagged" in scripts). It writes an ordinary 3MF in which every triangle also names the B-rep face it lies on, with the tessellation's own double-precision coordinates. Meshing and analysis tools can use the tags to keep a model's faces for loads or boundary conditions; a slicer that doesn't know the tags simply ignores them, so the file still prints.
Bringing a slicer's file back in
SolidCraft reads 3MF, STL and OBJ as mesh bodies. Each imported file arrives as a new component named after the file, so its bodies never mix with yours, and undo removes the whole import in one step. A 3MF project saved by a slicer comes in too, even when it keeps each object in its own model part inside the file (the 3MF Production extension): each object on the build plate becomes a mesh body, placed where the slicer put it.
Two limits to know:
- Mesh bodies render, measure, move and export, but solid features need B-rep bodies. You cannot fillet or shell a raw STL.
- For closed mechanical meshes with a constant cross-section, the
mesh.convertcommand (command palette, scripts and the control channel) rebuilds the mesh as a parametric solid with planar and circular cylindrical faces. Other shapes stay as meshes.
If you have a STEP file of the part instead, open that: it comes in as true solids. See SolidCraft STEP files.
Check mass before you print
SolidCraft's physical materials carry a density, and Properties reports the mass of a body or component with that material assigned. The README demo does exactly this with PETG. Physical properties also account for component and occurrence placements and repeated instances, so an assembly of several printed parts reports the total.
Combined with the measure commands (volume, area, centre of mass), that gives you a rough filament estimate before the slicer, and a quick sanity check that a hollowed part is really hollow.
What SolidCraft does not do
Worth stating plainly, because "SolidCraft CAM" is a common search:
- No slicing. SolidCraft produces the geometry; your slicer produces the G-code.
- No CAM or toolpaths. Manufacture/CAM is listed as "deferred until further notice" on the roadmap, together with simulation, rendering workspaces and 2D drawings.
- No mesh sculpting. Mesh and T-spline form modelling are also deferred. Imported meshes can be placed and exported, not edited.
For a printed part this rarely matters. For CNC work it does, so pair SolidCraft with a separate CAM program through STEP or STL.
A short printing workflow
- Sketch and extrude the part on the home page's launcher or in the desktop app, using named parameters for wall thickness and clearances.
- Assign a physical material and read the mass in Properties.
- File → Export 3MF…, fill in Design Properties if you share files, tick Send to slicer.
- Print the test piece. Change the parameter that was wrong, export again.
Prefer the desktop app for the Send to slicer button; the SolidCraft download page lists every installer. For the rest of the file formats, including STEP, IGES and URDF, the SolidCraft STEP files guide and the official import and export table cover them.