You can make these simple LED ghosties (based on LED throwies) from a soda bottle, a couple of LEDs and batteries, string, and a scrap of fabric. Hang them in your trees, your haunted house, or in your porch for Halloween. They look especially excellent because the eyes seem to float in mid-air behind the fabric.
Poke holes in a soda bottle on either side of the neck to thread your string through. This will help keep it facing forward when you hang it up.
Cut a slit in the back of your soda bottle to stick your LEDs through. Diffused LEDs are perfect for this since they won’t project a spot on your fabric. Red might make a more menacing, but you can use pretty much any color you like.
Bend the leads at 90 degrees so that you can tape the battery to the outside of the bottle later.
Once you have both LEDs in, put a 3V lithium coin cell (e.g. 2032) between the leads of the first LED. If it lights up, tape it in place. If not, turn the battery around so that it lights up and tape it in place.