Conversion from U3D to SLDPRT is not supported yet :(

Universal 3D (U3D) is a compressed file format standard for 3D computer graphics data.

The format was defined by a special consortium called 3D Industry Forum that brought together a diverse group of companies and organizations, including Intel, Boeing, HP, Adobe Systems, Bentley Systems, Right Hemisphere and others whose main focus had been the promotional development of 3D graphics for use in various industries, specifically at this time manufacturing as well as construction and industrial plant design. The format was later standardized by Ecma International in August 2005 as ECMA-363.

The goal is a universal standard for three-dimensional data of all kinds, to facilitate data exchange. The consortium promoted also the development of an open source library for facilitating the adoption of the format.

A SLDPRT file contains a 3D part created in the SOLIDWORKS design software.

Multiple SLDPRT parts can be independently modified and combined into a single SLDASM assembly file. If one SLDPRT part belongs to several assemblies, then after modifying it, the changes will appear in all assemblies.

SLDPRT are proprietary files with closed specifications. Nevertheless, some APIs (like CAD Exchanger SDK) provide the facility to read and convert them to other formats.

In addition to SOLIDWORKS software, SLDPRT files are supported by Autodesk Fusion 360.