[header] How to decorate with alien cocoons for halloween [title] Create a backdrop for your lair, unless your walls look creepy enough to show through. [step] Lay out a roll of dark paper or fabric large enough to cover your space, and spray paint them to add dimension and give them the color you want. [title] Cut and hang the backdrop. 
[step] This is like wallpapering, only not as precise or sturdy. Measure the height of your walls and cut sheets three or four inches longer off your prepared paper or cloth.