I've got one more little thing to add to the papier mache-ers:
Sometimes, I have two students work together to cover an entire balloon;
when dry, I ask them to cut in half and each has a half-sphere to use
Since I started this with my classes, I've been able to do succesful
mask (or funny face) projects with even Kinders.
And I use the tissue as the last cover almost always since I tried it
the first time - it's fantastic! It goes on easily and the projects
look amazing! And, best of all, we can do all of the papering in one
class, and be ready for gluing on the extras the next class.