1

Create an SCN file using 3D creation and editing software.

2

Import the CAD 3DS file into your SCN file.

If there's any unneccessary objects in your 3D file, you can edit or delete them.

3

Export the file as a Collada digital asset exchange (DAE) file.

4

Import the DAE file into an integrated development environment or file conversion software that can convert DAE files to SCN files.

5

Export the file in SCN format.

If you're using software capable of editing SCN files, you can correct wrong coordinates, add missing datas, or add textures.