Hi Folks
Believe it or not, such a thing exists.
You can actually write on it with traditional limestone chalk.
Note that the transfer method creates a much smoother surface that is functionally better than the direct print results.
Chalkboard Plastisol
What I can't confirm at the moment is price and availability.
Usually, minimums on a product like this are an issue, but let me see what I can come up with.
Happy trails!