Here's how we did it:
Cut four 18" pieces out of 1 x 4's. Sand them.
Cut two slats from a 1x3 and hot glue them across the 1x4's.
Spray paint the front with two coats of your choice of color. We used white. You can also do a base color that's darker, then a lighter color so that the darker color pops through when you sand it again (the picture below is after sanding off some of the paint).
Finally, do your design on paper, use whatever transfer process you want to trace it on the board. I used a darker color of chalk and penciled over it like I do for all my chalkboard designs.
Emily used just black paint on her design, I added some color for this wedding gift. Final step, add a sawtooth picture hanger to the back and you're done!
And here it is displayed in her home!