Materials you will need.
1 wire hanger
1 Propane torch
1 lighter or other ignition device
1 pair of vise grip pliers
3 pieces of scrap 2 x 4 lumber
Step 1: Making the Cutter
Alternatively you could create any shape with the wire hanger to fit your needs. Making a box shape would also work quite well.
Step 2: Make Your Cutting Table, Marking and Aligning.
Now mark or trace your foam where it needs to be cut and place it on your cutting table. Align the styrofoam flush to the bottom edge of the fence. Next align your cutting mark on the outer edge of the fence.
Step 3: Whoa There Pyro!
Ignite your torch and place it within arms reach of your work area while pointing it away from yourself and your work pieces. Take your cutting tool and place it in the path of the flame. Aligning the wire parallel within the flame will help to heat a large area of the wire. Leave the cutting tool in the flame long enough for it to emit a red glow. Once the wire is glowing your ready to cut.
Take your cutting tool and run it along the ground and the outer edge of the fence. Be sure to guide the rear part of the hanger into the cutting line. If not it may snag on the outside of the foam and stop your progress. If all goes well you should have achieved a nice straight line. Now your free to make as many cuts as you like but make sure your Momma/Wife/Girl friend doesn't catch you burnin her clothes hangers!
Last but not least, recycle your scraps.