Whether building a dollhouse or camping in the wild, sometimes you need something approaching a mirror but none is handy. You can create a mirror easily with creativity and observation. Humans have used and made reflecting surfaces for millennia, so start looking around.
Take aluminum foil, turn it shiny side up and press it onto a small round or oval of cardboard. It should stick to the surface without adhesive if you crimp it over the edges. Glue this to a paddle to make a hand mirror, or a frame to make a wall mirror for a doll house. The foil from a stick of gum also works. Flatten with your fingernail carefully to keep from breaking it.
Use the inside of an energy bar wrapper. Clean it carefully, bending the surface as little as possible. Trim it to the size of a stabilizer such as a flat piece of cardboard. Carefully tape it down with duct take. The fewer wrinkles it has, the less distortion in your mirror. Add a string on top to hang it from.
Look first to manmade objects such as knives or plates as mirrors in the wild. If a compass is large enough, it should serve. Obviously, aluminum foil or clear wrap you brought with you will work. A pan of water, left to settle, serves as a mirror, although for shaving it is less than ideal. Your best bet is to duct tape your largest shiny surface (the back of a plate or knife) to a tree while you shave.
Turn any chrome surface or window on a car into a temporary mirror to check your look. Spoons or large knives also work if you just want to apply lipstick or check your hair. Although such surfaces frequently distort the image they reflect, they serve your temporary purpose.