Used to define the openings or negative spaces within the cross section shape.

1. Select either

   Edit > Draw Internal Contour

   or

   the Internal Contour tool

2. Click any point in the View window as the first vertex of the inner contour. A line is rubber-banded between this point and the mouse pointer.
3. Click subsequent points to form additional vertices.
   Tip: You may right-click to undo a previous vertex.
4. Double click the final point once you have formed a closed geometric shape. The final point does not need to be a previously entered data point. The rubber band to the first point will give you a preview of what the shape will look like for any point in the View window. The shading inside of the shape is removed.
5. Exit the internal contour drawing mode by either

   repeating step one

   or

   select some other drawing mode