Sparse infill density (infill_density)

Sparse infill density is a number in %. Density of internal sparse infill.

What does each slicer call it?

Five slicers, five spellings of one setting. The scope column is which preset the key belongs to, which is what decides whether changing it follows the printer, the filament, or the print profile.

Where does it live in the file?

All five slicers file this under the process preset, so its value follows the print profile rather than the model. A .3mf is a zip, so unzip it and search for fill_density, sparse_infill_density and infill_sparse_density, or open the file in preslice and read the Raw tab, which searches every member at once.

Four of the five slicers write their settings into a sidecar part beside the geometry. Cura writes them into the model XML itself, so there is no config part to open.

What values are valid?

Each slicer declares its own type, default, and bounds for its key. They do not always agree, and where they disagree the file is still valid in both: the slicer that wrote it is the one that enforced its own rule.

The slicers disagree on the type: Cura as float, Creality Print as floatOrPercent, PrusaSlicer, Bambu Studio and OrcaSlicer as percent. preslice reads all of them.

Every type, default, and bound above is read from the slicer's own field definitions rather than from measurement: PrusaSlicer's PrintConfig.cpp, Bambu Studio's PrintConfig.cpp, OrcaSlicer's PrintConfig.cpp, Cura's fdmprinter.def.json and Creality Print's PrintConfig.cpp.

Can I read it from my own file?

Yes, without installing a slicer. Open preslice and drop a .3mf on the page. It unzips and parses the file in your browser, and shows sparse infill density under its own name alongside the rest of the print settings. The file never leaves your machine, and nothing uploads.