STL Import for Inventor is a Stereolithography (.stl) file import add-in for Inventor. This add-in gives Inventor the ability to import polygon data from ASCII and Binary STL files. STL Import for Inventor reads polygon mesh data stored in STL files and imports it into Inventor. A polygon mesh in a STL file is comprised of a set of triangular faces. STL Import for Inventor creates trimmed planar surfaces for each triangle/quad and knits them together to create a body. If the polygon mesh is closed (it does not contain boundary edges) then STL Import for Inventor will create a closed body feature, otherwise an open surface will be created.