I recently purchased a tin of small alphabet cookie cutters. The letters allow me to spell out things and personalize lunch in a special way. I also own mini farm animals, basic shapes, and seasonal mini cookie cutters. To be quite honest I think the heart may have shown up from the playdough toys, so be creative! Use what's on hand.
I also use a wooden spoon and a bamboo skewer to create the shapes. You'll find pressing through fruit leather needs a bit of pressure, if you just simply lay the spoon down and then press evenly on the cutter, it will be a much easier task. Our fruit leather of choice is the Stretch Island Fruit Co, but occasionally we are sent some from Trader Joe's which the girls love as well.
I try to use the cookie cutters in a way that maximizes as much fruit leather as possible. I never throw away the remaining fruit leather strip with the cut outs, I hand it off to my daughter to enjoy during her car ride to school.
A tip from experience, the fruit leather by nature is rather sticky. I always have a bamboo skewer out to use to help me release the fruit from the cookie cutter.
Sometimes I place the fruit leather shapes on top of a sandwich, you could even use the fruit leather to make faces! Or other times I just use it as a decoration in another compartment of the bento, maybe on a piece of fruit or rice.
I never consider the fruit leather as part of the lunch to replace fresh fruit. The fruit leather is a decorative bonus, which I am assuming always gets nibbled up first! A cute, quick way to add a little pizzaz to your bento lunch.