The mold is solid poplar. I use poplar because it's stable and easy to machine. When I made patterns back in the old days, we used mahogany on everything, when we couldnt get mahogany, we used poplar. I prime the wood so I can see any imperfections in the surface of the mold. Its easier to sand and see what needs to be adjusted. You cant see half as much if its just natural wood grain. I set up the mold and scribed in the rib locations and just continued around the form. Even though the rib doesnt follow the line due to the taper, it acts just as a reference to make sure I'm not off side to side. No, Gil, I dont use scale hammers and tack irons!!!!!! Stay tuned for porcupine marks!