How do I cut on the inside of a polygon using CAMBAM?

The apply a machining operation that cuts along the inside of a polygon, you will need to use the profile machining operation located at the top of the user interface, the first icon in red to the left. Hovering over the icons will inform you of what machining operation the icon represents. Select the polygon and click on the profile icon. A new profile operation will be created in the left drawing pane (outline of machining operations). Underneath the drawing pane, there is another pane with parameters for the profile listed. Find the Inside/Outside parameter and click just right of that parameter to change the setting to inside.