Turn , ah you have a lathe. you are set if you spend the time then.
i’ve often wondered if the material from billiard balls would work nicely for this.
I tried turning some wood ones. what I ended up doing was getting a piece of flat high carbon steel , think it was a blade from an oil type rotary compressor. I cut it to the profile I wanted with a dremil, then used that as a cutter rather than trying to follow the identical profile twice. I did a few wood knobs like that on the metal lathe. worked quite well.