Those "ugly sweater masks" look pretty neat - might be a fun project to bring in supplies and let my coworkers create their own. But since most of the fun is doing it together it might not be the best idea. I love doing stuff like that for team building. One year I brought in supplies so we could each make a gingerbread house. I have two molds for houses that finish about 6" square so they aren't supper big.
Here are the masks I made, don't have all the ties sewn yet.
First set