 Command entry:
Command entry:mental ray material 

 Advanced Shaders rollout 

 Click Contour button. 

 Choose Curvature (contour).
            
 Command entry:
Command entry:Other material 

 mental Ray Connection rollout 

 Advanced Shaders group 

 Unlock Contour if necessary. 

 Click Contour button. 

 Choose Curvature (contour).
            
 The Curvature contour shader traces a line whose thickness depends on the angle between normals of adjacent faces.
         So if two normals are in nearly opposite directions, there is a contour of width close to Max Width between them. As the angle
            between them decreases, the width of the contour decreases almost to Min Width.
         
          
            Interface
            
  - Color
- 
                   
                     The color used for rendering the contour lines.
                      
 
- Min Width (%)
- 
                   
                     The minimum contour width, in percent of the image size.
                      
 
- Max Width (%)
- 
                   
                     The maximum contour width, in percent of the image size.