A typical workflow begins with preparing a part for importing to the Additive application. From within a CAD program, such as Ansys SpaceClaim, you’ll need to export an .stl file. The standard file format for most rapid prototyping and 3D printing applications, an .stl file (from stereolithography) is a tessellated representation of a 3D object that consists of triangle elements that define the external surface of the object. Rather than being a volume representation, surface normal vectors define the inside versus the outside of the object.