I don't know that I'd choose to do this on a wall, but cool idea just the same. DIY project using a variety of colorful magazine pages cut into strips. Pick a silhouette/trace an outline. Then cut up the magazine strips and tape/glue it all together.
How to manage a group of twenty kids in a collaborative art project: circle painting project for kids // an oldie but a true goodie for sure, especially for numerous same aged children, or A Deep SpaceSparkle Art Project for