First, paint the back of your puzzle pieces with red or pink paint. We used acrylic paint.
Next, cut out a heart shape from a piece of cardboard and cover it with aluminum foil.
Hot glue your dry puzzle pieces around the perimeter of the heart. I recommend that you take a minute to figure out where you want your pieces before you start gluing.Attach a photo (or a few photos) to the center of your heart, and stick a magnet on the back. Here's another tip - always keep those free magnets; I use them for crafts. I just hot glue them to the back of whatever I want to turn into a magnet. You can cut them to whatever size you need. For this heart, I used two business card sized magnets. They work great.
Here is our finished Valentine on our refrigerator:
Here is our finished Valentine on our refrigerator: