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
Tray decorated with bottle caps. Instructions: spray painted bottle caps, paint a tray white, arrange dry caps on dried tray, next used "acrylic water" to pour over the caps. The acrylic hardens without incident & is ready for use!