Air Outside

Air Outside is a feature that allows you to indicate that only air will be present outside a given line - that all material will be removed outside the line. Similarly Air Inside is a feature that allows you to indicate that only air will be present inside a given line. For example to create a thru hole you would create a circle and set the line to Air Inside.

To indicate that a line is Air Outside or Air Inside:

1. Make sure the line is a closed line.
   
2. Go to the numeric bar's Z control.
3. Select Air Outside or Air Inside.
   

Drawing a shape in a side view and setting the shape to Air Outside is a useful method of creating a variety of shapes. 

For example, here is a Top view 2D drawing of a cylinder and its 3D rendering:

Now we will modify the shape of the above cylinder. We go to the Front view of the above cylinder design, draw the 2D shape shown on the left (the bolder line) and set Z to Air Outside. This results in the 3D rendering shown on the right.

Here we modify one of the shapes of the prior section by adding an Air Outside line in the Front view: