Follow the manufacturer's instructions for mixing the auto-body filler (we used Bondo brand). You will probably have to do a few applications to build up the area so that it will be flush with the surrounding area. Don't mix too much of the filler at once, as each application will set up and dry in about five minutes. NOTE: Only take on one damaged area at a time. It's best to repeat all the steps on each area that has been chewed.
Auto-body filler is a two-part epoxy. Use a small putty knife to mix it thoroughly (30 seconds) on a paper plate. Once you have enough filler covering the chewed area, let it dry to the touch, but don't wait too long — it should not completely harden or it will be difficult to carve off the excess. Slide a knife blade across the surface to slice off the extra filler and to roughly reshape the area that was damaged. It does not have to be exact; you can sand it down to the final shape.