1. Prepare you Router for the lettering by installing a straight bit set to cut about 1/4 inch deep. Also clamp the fronts of your tombstones to a solid surface so they won't move around when you start to shape.
2. Next route out where you want your picture to go. I did this by tracing the outside of the picture I found earlier and then going back and fourth with my router until I had a perfect inlay for my image to set in.
3. Next I sketched out a large crack on one of my graves and cut it out. On the other gravestone I traced around the foam skull and cut it out. I then divided the cutout piece into two parts so it would look like the skull broke through the tombstone when I reattach them later.
4. Paint all the lettering, the crack and the cut out parts black. This makes the lettering stand out more and hides any exposed particle board that might get missed later.
5. Lastly cut the back of the skull off so it will fit in the narrow tombstone. I used a hacksaw. It makes a pretty good mess, so do it in a location that is easy to sweep.