I was given another one of these large Arietites ammonites from the Early Jurassic Sinemurian to prepare recently. It turned out that it wasn't worth the effort for my friend, since it became obvious after a few hours of work that there weren't any more ribs to be found after a certain point. You can see this in the photo below. The arrow marks the point where the whorls disappeared and the ellipse shows another area where there were no ribs.
So he left it with me and I decided, what the heck, let's do a bit of carving just for fun. I used mostly the attachment on the air pen with the flat stylus until I approached the center and then changed over to the fine point. Took about 7 hours to get it done and now it's found a place out in the garden. I figure I could go into competition with the Moroccans now
Arietites solarium. 40cm.