After studying various purposes and types of masks found in West Africa, my art students were given the assignment to make a mask of their own. All of my classes were online this week, so students used the mat board and cardboard that I sent them, but cardboard from a cereal box would have worked fine too.
Most African masks are earth tones: black and browns, but there are some that have colorful beads or painted patterns. Start with a base coat, then add pattern with thinly painted lines and dots. Markers, especially Sharpies might be easier for this kind of mark making if the base is a light value. Any other embellishments such as feathers, beads, or yarn can be added for extra texture and color.