Google offers a huge open library of free 3D models,
http://sketchup.google.com/3dwarehouse/
Anyone can add to the library own models.
To open, edit model, create and publish your own 3D model, you need the program Google SketchUp
http://sketchup.google.com/intl/
There are 2 versions of 3D editor Google SketchUp
free version that allows to work with 3D models, create scenes, but does not allow to export the models and scenes to other CAD formats.
the paid version - Google SketchUp Pro, allowing to export models and scenes to other CAD formats (including *. 3ds, *. dxf, *. dwg).
paid version has a free trial period
File formats such as *. 3ds, *. dxf, *. dwg can be opened by the program 3DS MAX.
3DS MAX - paid 3D editor from Autodesk Inc.
VideoCAD offers a free package for importing 3D models and scenes from the 3DS MAX Import of 3D models and scenes from 3ds max to VideoCAD
Thus any of the 3D models from Google libraries can be imported into VideoCAD using 3DS MAX. You can create in Google SketchUp Pro entire scenes and import them to VideoCAD.