We built one in a college class some years ago (damn I sound old) Used two wood lathes tail to tail. Had a carriage powered by one lathe, rotation by the other. Pattern and blank were parallel to each other. Kind of like two chickens on a spits. Industrial router travelled on the carriage, attached to an inverted A frame that followed the pattern. We used it to produce 20+ stocks for flintlock rifles we were mass producing. Everybody in the class got a full kit when the class was done. Bought the locks and barrels as we didn't want the risk of making our own. Mine came out beautifully. Best balanced rifle I own.
Can't do that project in college any more -