ARTS AND CRAFTS FOR AFTER SCHOOL KIDS!!?

Hey guys, so I volunteer at a after school program and I'm trying to think of a project or activity to do with the kids but I need help. My classroom is made up of kids from kindergarten to fourth grade so it is a bit of range of kids and there are about thirty of them. I have to think of something that I can do with all of them so it can't be too much for a younger child but also not too complicated that the younger kids can't do it. I would also need to buy the supplies on my own so some more affordable ideas would be great! thanks in advance