I'd like to have my nephew (4) and niece (2.5) over for a fun Christmasy afternoon, and hopefully make it an annual tradition. I don't have any kids yet and although I've babysat them often, I've never done any sort of special activities with them.

Any ideas for easy (not super messy) crafts or fun food to make with them? I was thinking of doing a gingerbread house or decorating sugar cookies, but one of them is gluten-free.

Thanks!