Better day than yesterday for this, weather-wise. Did some research first and asked Google for 'Gravestone rubbings how to'. Plenty of sites with info. Suggested using rice paper or interfacing, a sewing material that I happened to have. I went to the Antietam Battlefield (U.S. Civil War) near our home where there is this lovely little cemetery with graves that date back to the 1700s. (This is a big deal for Americans.) I tried different materials like conte crayon, graphite, charcoal, and settled on a charcoal pencil for best result. The interfacing worked better than paper because it is more flexible without tearing and see-through, making it easier to position over the letter. Smooth stones with well-defined letters work best. A little drawing stool would have made it easier, instead of having to crouch down (grass was wet!). Couldn't help thinking this would be a fun thing to do with kids, having them find letters to spell words. Because the interfacing happened to have a heat-activated backing (you can get it without) I ironed the rubbing to a piece of fabric.