I can show you how to make a neck sheath. A better option might be a baldric carry, slung across your shoulder so the sheath sits at your right side and could be invisible under your jacket. It would have a small hole in the bottom so you could put a thong through to tuck into your belt. That way when you lean forward or bend down the sheath doesn't come swinging round in front of you, but can still be easily accessed with a left hand (in your case) cross draw. Hope that makes sense, sorry I don't have any pictures.
Eric