Some sample stl images can be loaded from the following buttons for viewing:

            
For time being only keys are being used to re-position model, click inside view-port to enable them:  
* Arrow keys for rotating.  
* 'q' makes model larger  
* 'e' makes model smaller  
* 'w' lowers the model  
* 's' elevates the model  
* 'a' moves model right  
* 'd' moves model left