Conversion from STL to IPT is not supported yet :(

STL (STereoLithography) is a file format native to the stereolithography CAD software. This file format is supported by many other software packages; it is widely used for rapid prototyping, 3D printing and computer-aided manufacturing. STL files describe only the surface geometry of a three-dimensional object without any representation of color, texture or other common CAD model attributes. The STL format specifies both ASCII and binary representations. Binary files are more common, since they are more compact.

An IPT file extension is used for Autodesk Inventor objects.

Autodesk Inventor is a CAD application that engineers and product designers use to construct prototypes of mechanical products. These prototypes, referred to as assemblies, consist of several individual parts joined together. Each Inventor part is saved in an IPT file.

Inventor users can import IPT parts from outside the program or create their IPT parts using the Inventor's part design tools. Typically, users begin by creating a 2D drawing of a part before transforming that drawing into a 3D model. Thus, an IPT file may contain either a 2D or 3D object. Files in IPT format can be opened using Autodesk Inventor 2017, Autodesk Inventor View 2017, Autodesk Fusion 360, and SpaceClaim Engineer.