Graphics files saved in 3D Studio Max are well supported in various 3D graphics, or even CAD software so it should be not that hard to find a software capable of conversion of 3DS model to ISO STEP format.
Convert 3ds Max (3D Studio MAX) graphics to ISO-10303 STEP product data.
We found 9 software records in the database related to .3ds to .step file format conversion.
Microsoft Windows software - convert 3ds to step on Windows
3D viewer and converter with huge file type support
Convert from 3ds file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned 3ds to step. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
A 3D model converter
Leading 2D and 3D CAD development software from Autodesk
A family of 2D/3D CAD software products for Windows
A widely-used 3D animation application from Autodesk
A converter for 3D formats
A CAD viewer program with conversion capabilities
Apple macOS / Mac OS X software - convert 3ds to step on OS X
Mac version of popular Autodesk AutoCAD software
A 2D/3D CAD software for OS X