I'm with Bill. Go to a jeweler or engraving/trophy shop and have it engraved.
For a really neat effect, you can engrave the customers name and "1 of 1" on the elk. Have the engraver use a fine tip stylus. Back at home. fill it with black paint ,or India ink, and immediately wipe off the excess. Let dry and sand lightly. It shows up as scrimshaw. It adds a custom look that is not common. Test this on a piece of scrap to make sure the paint doesn't absorb into the antler. Sometimes you have to "stabilize" and fill all the area around the engraving with CA ( before the engraving) to assure the paint stays only in the graver lines. The CA sands off and does'n show. Old timers used to wax bone with beeswax when doing scrimshaw to prevent the ink from soaking in where it is not wanted. when done, they buffed the bone and it took a nice shine from the wax. A lot of late 19th century fake ivory scrim was from the orient done this way on bone.....and they are still doing it.