Back in the 1930s and a little bit of the early 1940s, the Green Hornet was a series on the radio. After coming to television, the Green Hornet had a huge increase in popularity, and replicas from the show became popular, valuable collectibles. Bruce Lee acted as a very memorable Kato, while Van Williams made a phenomenal impact as the Green Hornet. Perhaps the most memorable item from the Green Hornet's show was the mask that was worn. It's rather easy to replicate this mask.
To make a Green Hornet mask, get any old mask that is raised in the eyebrow area. The kind of mask you are looking for is commonly referred to as a half mask, which covers the nose and most of the upper cheek. Either buy it in green or spray it with a green paint. The best kind would be to use an acrylic craft paint found in any common arts and crafts store. The kind of green you are going for is the sort that the army commonly uses for their bases and uniforms. It may simply be called army green or referred to by its more common name, olive green. Be sure to take some sandpaper and lightly rough up the paint once the half mask is painted.
The next thing you will need is yellow paper that is sticky on the back. An example of this would be a post-it, but perhaps it would be better to find yellow paper that is completely and fully sticky on the backside. Yellow sticky paper is the best candidate for this part of the procedure. By finding the insignia of the Green Hornet and printing it onto the yellow sticky paper, you can create your own sticker of the insignia! Cut out the circle and place the sticker right above the middle of the eyes. If you cannot find yellow sticky paper, it is likely that these sorts of stickers are sold on the web. Go ahead and search for them and they should come up at a rather inexpensive price.
If you would like to go ahead and complete the set, therefore going all out with the costume if you are, for example, going to a costume party or offering any sort of promotional campaign involving the Green Hornet, find yourself a matching olive green or army green colored hat. The kind of hat you'd be searching for would be called a fedora. Should you be unable to find the proper colored fedora, don't forget you can go out to the arts and crafts store and pick up some olive green or army green fabric paint. Add a green trench coat (don't forget the fabric paint if necessary!) to complete the set and you have yourself an easily made Green Hornet mask and outfit!