With the remaining plane iron, I built a Japanese Kiridashi style scoring / scribing knife.  I can imagine that the treatment of the metal is as important as the shape, but for this instance, it is the shape which I replicated.  I flattened, as best I could one side of the plane iron, and cut the shape I desired using the angle grinder.  Flattening was a long processes but worth the effort to get a sharp edge when putting the bevel on the other side.  The scrap metal was quite grubby to begin with, and I kept one side intact so to add a little authenticity to the artefact.  The flatness of one side allows the knife to be places directly against the material being scribe against.