A suitable 3D file is always required as the basis of the 3D printing. The 3D model and information such as dimensions, volume, wall thickness and resolution that are relevant for production are stored in these files. The standard format for additive manufacturing is the so-called STL format (standard triangulation language/standard tessellation language). It was developed back in the 1980s by Charles “Chuck” Hull, the inventor of stereolithography, and is currently still the most frequently used file format in 3D printing. The surfaces of 3D models are described in the form of triangles in STL files, whereby a normal vector defines the interior and exterior of the model. Since only the geometry of the model that is to be printed is described in an STL file, additional information such as color or material must also be recorded.

Prior to printing, the model is broken down into thin layers in so-called “slices”, which the 3D printer is able to read and print in succession. In addition to STL, there are many additional file formats that are used in 3D printing, such as OBJ, 3DM, ACIS, 3MF or AMF. In cases of doubt, a 3D printing service provider can provide information about which file formats their 3D printers support.