You can download PowerPoint slides containing 3D models that you see on this web site–the models are fully rotatable.  There are two conditions to enable viewing of 3D models on your PC.  First, you need to be running a version of Windows.  Second, you need to have an Active X control installed–you can do it by simply installing the free 3DCT Viewer.  We have been using these 3D models in our lectures with great responses from students.  Enjoy!