Conversion from STL to PRT 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.

A PRT format is used to store components of 3D CAD models. It may contain lines, surfaces, textures, dimensions, and metadata.

The .prt extension is mostly associated with the Siemens NX Part (PRT) file type as an acronym for "part". PRT files may be exported to various standard CAD and 3D modeling formats (e.g. OBJ and STL) in addition to being utilized natively in Siemens NX.

The PRT file is also a part created by PTC Creo Parametric 3D software. In PTC Creo, project part files can be combined in a single assembly file with an ASM extension.

Despite the same extension name different CAD software produce PRT files differently, i.e. PRT files produced with Creo are not the same as PRT files generated from NX.

The PRT extension is also compatible with Dassault Systèmes SOLIDWORKS.