First, you need the following:
Magnet Board (I used this one from Ikea)
Chalkboard Spray Paint - I am including an affiliate link below to the product I used.
Line up the edge of the painters tape, along the edge of the magnet board and apply on all edges.
Then cover the exposed sides with more painters tape to protect from overspray.
Press the edge of the tape down on the magnet board with your fingers and then run the back of a spoon along the edge to seal it as well as possible.
Take the prepared board outside, or to a well-ventilated area and spray paint it with the chalkboard paint. Follow the directions on the can for best results. I needed to do three coats for even coverage.
Let the paint dry and then remove the painters tape. Now you have a nice little frame around the chalkboard surface. Resist the urge to start using your chalkboard right away. Let the paint cure for 24 hours.
Now, prime the chalkboard surface by running the edge of a piece of chalk over the entire surface. Then erase the chalk and your chalkboard is ready for use.
I also used this method to make a magnetic chalkboard menu for my kitchen.
The only difference is I used one of the silver magnet boards and wider painters tape to make the frame. Then I added white vinyl lettering. It turned out cute and is such a nice addition to our kitchen, that we are all enjoying.