After we set our beads in place I melted them. The Punk was safely in the living room playing Hotwheels, and I went at it. Parchment paper, iron and a washcloth was all I needed (The IKEA directions just show a stick figure and an iron, so I Googled some better instructions).
Paper under, paper over, press with a hot iron.
We ended up making 3 hearts today. I am thinking about gluing some magnets to the back so they can have a bit more purpose.