The kindergarten classes at my sons school do a "craft-o-rama" day the week before Christmas break. Each class has 5-6 parent volunteers come in and lead a Christmas/Winter themed craft. We design the craft ourselves, bring in a pre-made model and then the kids are split into small groups and go through each craft station.
Last year I made candy cane ornaments with them, and this year we made popsicle stick rudolphs.
The kids in class had a difficult time making a triangle with the popsicle sticks (the glue was wet, so they kept slipping off). Depending on your kids, you may want to make that part ahead of time so the glue can dry.
What you need:
Popsicle Sticks (3 per person)
Red paint or red pom poms (1 each) for the nose
Googly Eyes (2 each)
Construction paper antlers
Pipe Cleaner or ribbon (if you want to hang it on the tree)
If you want to paint the sticks brown, you could do that too. It would take a little while to dry before gluing them together.