3D stamp garland
You can not miss this space craft where the rockets and stars have a third dimension and are so easy to do that your children will enjoy dreaming astral universes.
The idea comes from Oh! My Handmade, stamping for duplicate a shape (symmetrical ones are recommended), such as two stars or two rockets, then cut them separately and make a vertical cut in one of the pieces. Finally fold your cut out prints together creating a cool 3D effect and hang them from a thin cord.
Repeat with as many pieces as you want to hang, cut and assembled together and just enjoy looking at them!