Slicing and 3D Printing File Types Overview

A slicer takes a 3D model, typically in the form of a STL or 3MF file, slices into layers, and creates instructions for Computer Numerical Control (CNC) manufacturing, of which 3D printing is a subset.

The standard language of the output instructions is GCode.

STL files describe 3D models using interlocking triangles, often referred to as a "mesh". STL is an abbreviation of the 3D printing technology stereolithography, but is alternatively defined as Standard Tesselation Language or Standard Triangle Language.

STLs contain very little information out side of the location of the model's triangles. One of the most impactful pieces of info omitted is units. All measurements in an STL are unitless.

The file extensions for STL files is .stl.

3MF files are a newer option. They are designed with 3D manufacturing in mind (3MF stands for 3D Manufacturing.)

3MF files most commonly describe geometry as a mesh of triangles, like STLs.

3MF files contain unit, color, and material information. Importantly, they can also contain slicer settings (printer, infill, walls, etc.)

The file extension for 3MF files is .3mf. Slicer settings do not transfer across different slicers.

Editing geometry in an STL or 3MF is called mesh editing. Slicers like Bambu Studio and Prusa Slicer provide some basic mesh editing tools. For more complex mesh editing, there are free programs like Blender and Meshmixer.

GCode is not a description of geometry in the same way as a STL or 3MF. Instead, it is a list of instructions for a manufacturing machine, like a 3D printer.

You do not have to write GCode manually. Instead, the slicer will create it for you. It can be useful to understand and edit GCode for advanced troubleshooting.

The file extension for GCode is .gcode or .bgcode