We cut these for companies that do Cast Stone and Cast Concrete. These letters are cut to the size and font specified. We use the Simulated Prismatic Technique with one twist - the letters are cut in reverse. Our customers then attach them to their molds, pour in the cement mixture, and when it has set they have a stone that looks as though it has had the letters chisled into it. Some people call them V-Cut or V-Carve Letters. Some call them Prismatic or Chisle-Cut. Using this process they can produce beautiful Date Stones, Dedication Stones and other Signs.
These are not the easiest things in the world to do. Several parameters affect the process. For example, the thickest stroke width of the letters determines the thickness of the material as well as the angle of the bevel. For larger, thicker letters, the bit will have to make several passes. Doing the math in order to create the correct tool path gets tricky in these cases. Another parameter would be how many times the mold will be used. This determines the best material to use - either going with inexpensive XPVC for single or limited uses or more expensive Duro-Tek for repeated use. If the letter depth is greater than 1.25" we would need to use either HDU Foam or thick sheets of XPVC laminated together.
One more point is that we do the final cutout with a tapered bit so that even the vertical return will release from the mold easily. You can kind of see this in the fuzzy picture below.
Following are photos of some finished wall signs by one of our customers.
