All you need is a piece of smooth plywood (I used a 4x8 piece), pieces of trim, chalkboard paint**, and paint for the trim. (and screws and nails to attach the trim to the board and the board to the fence.)
**Actual chalkboard paint is for indoor use only, but I needed something for outside. This idea was for an outdoor chalkboard and it was in a Lowe's magazine, so I ask the Lowe's paint guys what to use. They said that the paint that was in the magazine was black outdoor latex paint, so that's what we got.
After I put the first coat of paint on the board, I started painting the trim. This proved to be a problem, because Jeff got pvc trim so it would last longer outside. Well, the paint I bought did not want to stick to the trim, so Jeff suggested I sand the trim down first:
It worked! The rest of the trim was much easier to paint! I put 2 coats of paint on both the trim and the board. I had a quart of paint for each and I had a lot left over of the red, but I used almost all of the black.
Then I helped Jeff screw the board into the fence, making sure the screws went into the cross board on the back of the fence for support.
To give you an idea on how big this is, here is Lily standing next to it:
The next day, Jeff cut the trim for me.....
and nailed it up onto the board:
Then it was time to get the chalk out!