Old set of curtains.
Getting tired of the sun baking the side of your face until you get a massive head-splitting headache? Do you have a voyeur as your neighbor and you tire of them always scanning your private property with their binoculars? Why not block out both with curtains! Curtains can be made out of natural and synthetic textiles, and can be translucent or fully opaque. They come in many different colors, sizes, patterns, shapes and materials. Plus, they can make a bare room look a bit more comfortable.
Found in many department stores, houses, hospitals, theaters and curtain shops.