You can't appreciate the amount of work involved in mold making until you are asked to make one large or small the devil is in the fit and intricacy of design. Try making one for a 12x4.00x8 semi solid neoprene tire on a Bridgeport with full manual only with little more than an18" rotary table with a 36" face plate mounted on it as the only special tooling available Fortunately we started out with a 2" thick plate than had been Blanchard ground on both flat faces to make the upper and lower cavities the core started out as a 3 inch thick disk. the core was easy done mostly on the lathe, but the cavity plates were too large for me to chuck and swing in my lathe. Hallowing out the shapes of the tire wasn't too bad just a lot of material to be removed but when it came time to add the raised lettering of all the text that had to be done with a dermal and a template I made. All in all a fun though arduous project for a small machine shop just starting out back in the early 1990s