I was sorely in need of some chalk boards for use in the photobooth at our wedding reception. I did not originate this idea. It's been floating around the internet for a while. I did, however, act on this idea, which is more that I can say about most of the cute ideas I see on the internet.
What you need:
2 Thrifted Metal Trays (The dorkier the pattern, the better)
1 Can of Spray Paint
Follow the directions on the back of the can and voila! Cute chalkboards for your guest to leave you cute messages.