I always tell them that if they do a project just because they have to, it won't turn out as good as if it has some significance or is meaningful to them. So if they need to make a box, they should think about how they could use that box. It could hold jewelry or keys or spare change, etc. Or maybe they can place initials or a name on it or even a small sculpture on it to signify a special person.
Evaluation:
1 point -- Large enough to be hollow
2 points -- Artistic merit (make it meaningful)
3 points -- Unusual or original
4 points -- Quality and workmanship
10 points total