Conversion from Parasolid to 3DS is not supported yet :(

Parasolid

Parasolid file format is native for Parasolid geometrical kernel. Today it is widely used in a range of applications, including SolidWorks, SolidEdge, NX, Microstation, Ansys, Abaqus and others. Parasolid has two primary file extensions: .x_t, which is text based, and .x_b – binary-based format. Parasolid is also used to provide precise geometrical definitions of parts in JT files (as XT B-Rep data segments). CAD Exchanger can read files compliant with the entire range of Parasolid file format (schema) starting from v0.15 and up to version 32 (as of time of writing this page). Likewise, CAD Exchanger writes file compliant with all Parasolid schemas.

3DS

3DS is one of the file formats used by the Autodesk 3D modeling, animation and rendering software. It once was native for the old Autodesk 3D Studio DOS and eventually has grown to become a de facto industry standard for transferring models between 3D programs, or for storing models for 3D resource catalogs.

3DS is aimed at providing an import/export format, retaining only essential geometry, texture and lighting data.