Cutting foam and composites
Cutting foam is a very interesting way of using a CNC machine. You can shape a block of dense foam (available at most DIY stores) with a CNC machine and then lay-up fiberglass on it to create a very strong and light object. I have built parts of a full-sized airplane this way. The wings have a foam core that was then layered in fiberglass, but the shape was cut by machine (either hot wire or CNC). When cutting foam, you must have a high-speed spindle (10,000 RPM comes to mind) and very sharp bits to prevent shredding.
Foam also makes a lot of mess and it is always a good idea to mount a dust shoe/brush and hook the other end to a shop vacuum to suck up as much of the dust as possible. Wear a mask when cutting foam as you also don’t want any of that dust in your lungs. One use case for foam is to cut inserts into packing cases and enclosures (for example, a camera case). Make sure your cutting lines overlap in your toolpath files so that you don...