I showed my girls how to make clay hearts the other day. Lu (5 years old) was able to make them on her own after some hands on guidance. I think the ideal ages would be 6+. It is so simple I almost didn't post it! I figured, the simplest route is often the last one we try. So to save you some time....
You may ask yourself, why not use a cookie cutter? Well these little hearts are smaller than a cookie cutter and more rounded looking. They would make cute magnets or charms. Plus there is something satisfying molding something with your hands.
Roll some clay, model magic or salt dough into a small ball.
Flatten slightly with your palm or fingers. Not too much!
Squeeze one side, using your thumb and pointer, to create end of heart.
Snip with scissors the top part of heart.
Using your pointer finger, nudge the two piece apart. Round the top of each side by patting gently with your finger.
You can keep it like that or SQUISH it with your palm. This was my girls favorite part. Let dry and then glue magnet to back for a special Valentine's gift.
If making a charm poke a hole into clay before drying. Make sure hole is big enough to fit your yarn or ribbon. Also don't place too close to edge.