I had a chance to learn how to use a free 3D model-building soltware "Google SketchUp". You can download it from

 http://sketchup.google.com/download.html

You have to download the software in order to open and edit (play with)  my model.  You can also download the 3D viewer if you only want to be able to open and turn the models around.  To download the viewer, follow this link http://dl.google.com/sketchup/GoogleSketchUpViewerWEN.exe

It might seem difficult at first, but it is really not as hard as it looks. Check them out.

They even teach you how to use SketchUp in classroom. http://www.sketchup.com/?section=education