Using Handy Bandy I sawed off a piece of aluminum rod. I did not dare to use brass because it is expensive and not easy to obtain. About 20 minutes later...
... I had the shape you see above. The end looks rather like a ball and the other decoration is sort of an ellipsoid. All freehand. Whee! This is fun! Notice I was using the chuck. Not a good idea, because the tool can hit the chuck. So what is a graver?
A graver is nothing more than a chisel. I had this tool, which you see above. I had made it to cut threads on the pole lathe by chasing. I reground it. With it, I faced off (squared) the end of the bandsaw cut -- freehand. It takes quite some practice to learn how to use a graver. There are three axes (pitch, roll, yaw) and you have to get all three right. Note I am using the standard Taig wood-turning tool rest.
After a while I learned my wood-turning parting tool works just as well for cutting grooves in Aluminum as it does on wood. Not surprising, Steel much harder than Ally. So I learned to rough out with the parting tool and blend in with the graver.
Much more to learn. For instance, the chuck is a bad idea. It interferes with tool movement. So fortunately I have acquired a set of ER collets and an adapter to replace the Taig collets. This is a much better option than the chuck. More to come. Still learning, but it is very enjoyable.