I'm a bit late to the Chalkboard party, but I had to share the project!
Metal sheet, tray, etc. I'm using an oil drip pan from the auto supply store.
Chalkboard Paint (Mine is by Plaid, bought at Joanns)
Start with a clean sheet of metal or tray. I had this stored away for quite a while, planning to make a magnetic calendar with tape lines (You can still see the markings left by the tape I removed on the left side). It just never happened. It has the company logo stamped into the metal, but I'm hoping it won't cause too much of an issue. If worse comes to worse, it's magnetic so I could always cover it with one of the kids drawings or other piece of paper! :)
Use your chalkboard paint to put on a layer. I am trying to go in one direction and keep my coat thin and even.
Let the first coat dry for one hour.
Add another layer, going in the opposite direction. Let dry for one hour. Repeat until you have the tray covered evenly.
This the tray after 4 layers. Following the directions on the paint, I let the tray cure for 24 hours.
Then went over it with a light covering of chalk to "condition" the board. Then, wipe it off and you're ready to go! I can't wait to use this for menus, lists, messages to the family and lots of other things.