Autodesk Inventor allows you to save both individual parts and assemblies in STL format, at all design levels.

To save an Autodesk Inventor model design as an STL file:

1. From the Tools menu, select Rebuild All.
This ensures that the design data contains recent changes, and that it is not corrupt.
2. From the File menu, select Save Copy As…
> To Save copy as dialoge box opens
3. In the Save as type field, select STL Files (*.stl), and click Options.
The STLOut Save Options dialog box opens.