I finally got around to making the outlines (paper and glued to insulation foam) and using a dremel/router to etch out the design. There is no easy way to make a stencil unless you are an expert at Cricut and apply it to the foam board. I also recommend you run the router on low speed to control the lines better. I almost think it's better just to freehand the design because routing out the glued paper or the vinyl makes it more difficult versus just etching out the foam. Only after cutting the name and design will you seal the foam with a masonry sealer. Southern Makers recommend Drylok, a gritty, sandy texture to seal foam from water. However, one cannot find that product in Canada so when you run out like I did, just get a masonry sealer locally.
Paint the tombstones. Note that rain will make your paint run so you may wish to apply a clear sealant. Madam D then hot glued moss and leaves to the tombstones. Unfortunately, we discovered that many leaves were not colorfast and went white after seeing the ghost float...'er, after it rained.
