A very interesting thread. Polish collectors most often cast the knobs in resin, the texture of the printed materials is far from the original.
I will also add my little brick for 3D printing. So far I am very little advanced with my hobby 3D metal printer. I use an electron beam, but the texture and size of the prints is still far, far from what I would like to achieve.
If you want, you can watch this short movie.
https://www.youtube.com/watch?v=P4_zgzDZMe4