I don't think there is any concise secret formula that one could just copy to paper and readapt.
The article gives the impression there was a specific highly custom production system where the materials were selected for the machines and the machines were fit for the materials. And the machines were apparently jury rigged adaptations which probably lack detailed blueprints. Sounds a bit hard to formalize, after the fact, without quite a laborious effort.
I'd bet that, if he made some Youtube videos explaining the recipe, and the way it changes based on the local situation (and manufacturing equipment), as well as some videos giving a tour of the manufacturing equipment, some enterprising Makers would find a way to whip up a "Make your own Chalk" machine.
While it wouldn't be perfect, such a machine could be standardized or improved, and quality could be iterated on by people who care about it until they could make their own chalk that was better than what they can easily buy.
Heck, just the recipe might be sufficient for people to do that.
