I just bought DD a "showbag" from the market which has 4 tree decorations for her to make. they make heaps of little bags - PM if you want details. The bag cost $10.

You could also get the kids to make reindeer food. Last year we did oats with glitter in it for "magic power".

Read Christmas Stories

Make bon bons with old loo paper rolls and Christmas Paper

Riot has a heap of little christmas packs

What about getting them to do a painting with red and green paint to use as Wrapping Paper for Grandparents?