I'd like to make a forged sculpture of an ammonite, a "living" one, not a fossil. Not very big, 1" bar stock. I think I have all the details worked out, but am having trouble figuring out how to do the ridges on the shell, as they get progressively smaller. I'd post a picture but it's copywrited, I'm sure, so I'll put in a link to exactly what I want it to look like. I thought of hammering and chisels, edge of the anvil, etc.... but I want both sides identical. Any ideas would be appreciated.... Maybe I miss the obvious.
https://cdn.mos.cms.futurecdn.net/RNaW48QkpnKqTo9WtrQ3WV.jpg