If you need a cloudy background for a photo or video, you can always turn an old aquarium into a DIY cloud tank. But, if you want something more fun and less creepy, these fluffy cloud props by Serena Thompson might be more what you're looking for. It'd even make a good Halloween costume if you tweak it a little.
All you need is some balloons, tape, flour, newspaper, and a bunch of pillow stuffing. Serena made them by taping balloons together and applying a mixture of water and flour, then covering the balloons in strips of newspaper.
Once they dried, she used a spray adhesive to attach the stuffing all over the outside. And that's all there is to it. No more complicated than the papier-mâché crafts you forced your parents to display in the living room in elementary school, just a lot softer.
Check out Serena's tutorial for more details and photos.