This is an easy form of collage. Prepare the face and the open mouth and let the child decorate the monster. Here’s how:
After you cut out and fold the monster, crease the folds in every direction. Glue to another sheet of paper, but avoid putting any glue on the mouth or it won’t open.
Now it’s up to the child to decorate the card. You may want to add some legs to make the card stand upright.