I've gotten some comments about my heart-shaped tamagoyaki, so I thought people might be interested in knowing how to make heart-shaped food. ^_^ It's super simple, actually: all you need is oval-shaped food!
Cut the food diagonally like so:
Then flip one of the pieces over and put the two pieces together (along where it was cut) to make a heart:
For small but thick foods like tamagoyaki, you can use a toothpick (I bought reusable plastic ones designed specifically for use in bentos from the 100 yen shop) to hold the shape together.
There's actually another method that's great for bread which I learned from the manga-form essay book My Darling is a Foreigner 2 (Darling wa Gaikokujin) (p18):
^_^ I love ideas that are really simple but make you think "That's brilliant!" the first time you learn about them.
I hope everyone can enjoy heart-shaped food from now on! =D