STL Import for AutoCAD is a Stereolithography (.stl) file import add-in for AutoCADВ®. This plug-in gives AutoCAD the ability to import geometric data from ASCII and Binary STL files.STL Import for AutoCAD reads polygon mesh data stored in STL files and imports it into AutoCAD. A polygon mesh in a STL file is comprised of a set of triangular faces. STL Import for AutoCAD recreates the STL model data inside the active AutoCAD drawing.