Question for some of the more experienced engravers here. Aren't liners used for shading, not for cutting parallel lines? I have a couple of old double line engravers, I have no idea how old they are or what they were intended for (picked them up at a flea market), but the tips are wider apart than you would use for shading, more like what you see on this lock. Like I said, I have never mastered them, I cut two separate lines when doing borders as that is what appears to be the method used on colonial work and as Jim said, it is not that hard to do. My friend, who is a master engraver and is a member of the Firearms Engravers Guild, usually cuts parallel lines individually also but on occasion uses a double line graver for special applications. I know he makes a lot of his graving tools to fit certain uses, I have no idea if he made his double line gravers. Of course he does all his work under a microscope as he only works on modern stuff. Some of his work is so small, I can barely even see it with my #7 optivisors. I still vote for a double line graver on this lock after carefully studying enlargements of this picture, but I certainly defer to those with more knowledge.