You can make almost ANYTHING out of Rice Krispy treats...Christmas trees, bells, etc. They can decorate them with gumdrops, red hots, nerds, or whatever. You can use cookie cutters to shape them if you want. Will be quicker if you're doing alot of them.
Popcorn balls with some red & green candies mixed in for color. You could even "tie" a strand or two of twizzler for the bow on top, if you wanted.
One of the cutest things we did was to cut out a strip of brown paper about 3" high and about 6" -7" long. Glue the ends together to form a circle.
We then took ORANGES and put on antlers made of brown pipe cleaners, a red small pom ball for the nose and wiggle eyes. They were SO cute! I can still remember one of the little girls kept kissing hers. Many named them, as well. We used a straight pin to put the nose on, glued the wiggle eyes and the pipe cleaners can be shaped to fit the orange. Use a little glue if you want. Crayola now makes something called a GLUE ROLLER. I've thrown away SO many glue sticks. These things are GREAT and ALOT less messy. VERY cute!
There are always candy cane reindeer. Use a pipe cleaner for the antlers and glue wiggle eyes on either side of the curved part of the cane, just above the place where it curves the most.