Fondant Art
This sugary substance can be formed and molded in pretty much anything you have in mind; from the most delicate flower to a simple, smooth sheet of cake covering, and anything else in between.
The only requirement is that you eat it within two to three months, because that is how long you can actually keep fondant 'fresh' so to speak, but it would probably be a good idea to take some photos of your creations as soon as you are done, because the likelihood of it being consumed before that is great.
I came across some magnificent cakes which portrayed an entire scene and had the most intricate and detailed figurines on it.
You don't have to go out of your ways though to come up with something elaborate that catches the eye; a cute, little project like this will already yield the same results.
It is also a safe and enjoyable craft for the kids, as long as you keep in mind that you may have to contend with and suffer through their sugar buzz afterwards!
See also:
Fondant Art Part 2
Fondant Art - Materials and Equipment