Save / Save As / autosave.

Save As… (Ctrl+Shift+S) opens a file picker the first time. Pick a folder and filename. On Chromium, Layerpaint uses the File System Access API, so subsequent saves write the file silently in place. Other browsers fall back to a Blob download.

Save (Ctrl+S) writes to the current file.

Autosave toggle in the panel footer with a minutes input (default 3). Layerpaint runs Save automatically every N minutes.

.layerpaint files are gzipped JSON containing the welded mesh, all paint state, boundaries, palette, and symmetry. Re-opening restores everything exactly.

• Save As at the start of any meaningful session.
• Save (Ctrl+S) every 5 minutes at minimum, or rely on autosave.
• Autosave on for longer sessions — silent on Chromium, costs nothing.
• Always save .layerpaint files, not just exported 3MFs. The 3MF doesn't preserve auto-partition state, brush settings, or palette names.

1. Type a project name in the top-bar input.
2. Save As… (Ctrl+Shift+S) — pick a folder. Browser asks once; grant permission.
3. Save (Ctrl+S) — silent updates thereafter on Chromium.
4. Toggle Autosave in the panel footer. Set interval (default 3 min).
5. Reload: drag the saved .layerpaint file back onto the viewport — full restore.

• Browser asking on every save? FSA permission denied or non-Chromium browser. Firefox/Safari fall back to Blob download.
• file:// origin doesn't have FSA — use a local server or layerpaint.app.
• Don't conflate 3MF with project file. Always save a .layerpaint alongside any export.