Purchase a can of Chalkboard spray paint and follow the directions on can for applying it.
I used paint tape to cover the edges where I did not want the chalkboard paint.
Once your paint is dry, follow the directions for preparing it to use as a chalkboard.
This mini-chalkboard will be used for a door sign. You could also use a small one for guests to write you a short note (when you are not home, out in the garden, or doing other outside work).