Cut adhesive back fun foam with a heart die. Then embossed the heart with a matching embossing folder.
I embossed two fun foam hearts, one each way in the same embossing folder. Here are the inked images:
To make the "stamps" more stable, adhered the stamps to cut out plastic packaging. Adhered the matching stamp images to the top of the plastic and used clear packing tape over the paper for protection. Also made a couple of butterfly foam stamps.