what's the cheap DIY version of this?

>Save thousands over stripping and re-anodizing damaged parts. Much better than using a black marker or paint, the solution chemically converts the aluminum into a black color with a permanent repair. Won't chip, peel or rub off.
https://forums.pelicanparts.com/porsche-911-technical-forum/1071029-restoring-black-anodizing-easy-peasy.html