Bottle Cap Magnets These bright little bobbles were created by Catherine from The Pink Doormat. Materials: bottle caps, magnets, mounting tape, white nail polish, and a variety of other nail polish colors. 1. Stick the magnet to the back of your bottle cap using mounting tape. You can also use hot glue if you have it. 2. Paint 2-3 coats of white nail polish on your bottle cap. Let it dry for a couple of minutes. This white paint will be your background. 3. Lightly add dots with the nail polish brush. Repeat this step for each color you’d like to add, and wait for a few minutes between each color to allow for drying. 4. Apply a coat of clear nail polish on the bottle caps for extra shine.