I honestly thought these were earings first. But it is a cool idea: A homey take on the traditional locket, bottle caps inset with small black-and-white pictures, above, can be used as thumbtacks or magnets. Magnet and Thumbtack How-To
Glue thumb tacks on the back, add cute paper on the front, perfect for displaying projects on a bullitin board! You can also put a magnet on the back instead of the thumb tack and put it on a white board!
Make the plain white thumbtacks on your bulletin board cuter. And by cuter, I mean oranger. put a small piece of washi tape on each pushpin, smoothed out any fine wrinkles with your thumbnail, and trimmed around the edges with a sharp scissors.