Cheap Chinese batteries are still around, and they still have the carbon rod in them. The regular black Ever Ready battery range here is an example, though those may still be made in South Africa. I have not looked for a while.
I used to take D cells and use the carbon rod as a welding rod, it works quite well to do small sheet metal work. You cook it a little in a fire to get the wax out, wind the end with a copper wire for better contact, and use a pencil sharpener to make the other end pointy. made microphones using them and 2 halves of a Minora razor blade ( just think that as a kid I could go into a shop and buy bare razor blades no questions asked, and walk around with a knife as well. Could even buy fireworks and matches, along with cigarettes, but no alcohol) on a wooden block along with an old speaker and some wire and the remaining D cell as power.
It was a great video. I would like to hear more, and don't get scared of getting too technical. The more the merrier.
A Fiat will get you from point A to point B. So why do people buy Ferraris?
A Ferrari is a Fiat!
And a Lotus is a Proton! I still love mine