I saw this idea on a TV show several years ago and recently remembered it. You start with these plastic sheets (I got mine at Hobby Lobby, in the same aisle as the candle and soap making supplies), black puffy paint, and a coloring page. I chose Elmo because he is a character that my daughter happens to like, and he is fairly easy. Only 2 colors, and not a lot of detail. I highly recommend starting out with a very easy design. You can look through coloring books to find an image, or you can just google "Elmo coloring pages" or any kind of coloring pages, for that matter. I think it's better to google an image because that way you have a lot more choices.
Take the plastic wrap off both sides of your plastic sheet. Tape the coloring page under the plastic sheet. Using a steady hand. trace around the design with puffy paint.
Let dry for several hours.
Once dry, mix Elmer's glue with food coloring in the colors you will need. I only needed orange (for the nose) and red. I used a section of an egg carton to mix up the colors.
Use Q-tips to apply the colored glue to the design. Let dry for several hours. Then, hang in a window for all to see!