Make chalkboard out of slate and wood. Chalkboard eraser can be made from felt or wool or something. Add both material costs together to make the building.
Make chalk out of limestone. Carryable by hand, stacks up to 20 or something, maybe you can craft a box to store lots of chalk (like a keyring storing keys)
Big board where someone can go to write a message up to idk... like 300 characters or something reasonable.
Erase it when you're done or need to write something else.
Chalk is consumed per character per message.
Useful for multi-person camps where someone (the chef in our case) needs to make a grocery/foraging list for his buddies to look at when he's offline so they know what they need to go grab for him to make the best food.
Erasing feature helps cook update the list daily without being too costly.