TO EXPORT A MODEL OR DRAWING FROM AUTOCAD:
AutoCAD offers a small number of writeable file formats. The most versatile and useful of these are the DWG and DXF formats. Use AutoCAD’s SAVEAS command to export your AutoCAD work in several versions of these formats. (Note, for example, that some software cannot read a 2010 DWG or a 2013 DWG file, so that you may need to SAVEAS a 2007 DWG file to ensure legibilty.)
AutoCAD’s WBLOCK (Write Block) command is useful if you want to export just part of a drawing or model to a new DWG file.
AutoCAD’s EXPORT command is minimally useful: it allows you to export your AutoCAD information in one of a few non-AutoCAD formats.
TO IMPORT A MODEL OR DRAWING TO AUTOCAD:
To get the best results for importing vector information to AutoCAD, the vector information should be previously saved in the DWG or DXF format. Most modeling and drawing software (Rhino, SketchUp, Revit, Illustrator) can write information in one or both of these formats. Use AutoCAD’s File > Open command to open files of either type (DWG or DXF).
AutoCAD also has an IMPORT command which is minimally useful in opening files of non-AutoCAD format.
Edit > Paste can be of use in specific situations when copying and pasting vector information from one document to another.