Imaginality Create (http://www.GetImaginality.com) is now tightly integrated with SketchUp so that it can install it automatically, and then jump from one to the other with ease. If you haven't tried SketchUp yet - it's a free application that makes it easy to create your own 3D models, or choose from an online library of 200,000+ free models.
You can also download the module created in this video to run it and modify it - from http://news.getimaginality.com/?p=5