There's a thing called a "lathe" which spins a thing round whilst you hold a chisel against it.
It's regarded as being easier than the converse - holding a thing still and spinning around it yourself, with a chisel in your hand, but try it by all means.
So people are handmaking these? I imagined there was some kind of machine that churns them out somehow. It sounds hard to do them with a lathe! Also, I once had a local wood working guy who had these big fancy machines make me about 12 wooden rings. They all came out perfect, how did he do it? And in the end, he didn't even charge me, so it must have been super easy.
Not sure where you are located (England is a pretty big place) but if you can find a wood turning club nearby then pop along and have a look at what they do. They will be more than happy to show off the 'how'.