A standard 3-axis portal mill:

Standard portal mill

A Staeubli RX90 robot with a milling head:

(Note to self: there are more colors besides grey!)
Staeubli RX90

The tool definition window:

Tool definition window

A generated cutaway-area (debugging output):

If the tool moves from one point to another the area that is cut away is calculated. This object can then be used in CSG operations.
Single toolpath