Almost every 3D modeling / CAD software or converter supports STEP product data files (.stp, .step), unfortunately the same cannot be said about the 3DS format from 3ds Max. This makes it extremely difficult for users to actually achieve step to 3ds conversion.
Open STEP file Open 3DS file3D viewer and converter with huge file type support
A converter for 3D formats
An online CAD conversion service
A commercial online CAD converter
A 3D CAD translation software