About a year ago I made a clip-on lens for my iPhone and everyone is always asking me where I got it. It's very easy to make with just a few tools and materials. I'm not the first person to make one of these, but this is my take on it.
Step 1: Gather the Materials and Tools
Tools: pliers, small drill bits, X-Acto knife and/or saw, fine metal file and/or sandpaper, hair dryer or heat gun, tweezers, wire cutters
Materials: 4" of .04" music wire, disposable camera, 1/16" heat shrink tubing (4"+, 1 or more colors), super glue or RTV, O-ring assortment
The camera can be one that you have and have used up and removed the film, or you can ask for a used one from a one hour photo lab.
Step 2: Cover and Bend the Wire
Snip the wire to length (4"), if you haven't already before covering the wire with the heat shrink.
Using the pliers, shape the wire as shown in the photo. Each of the sides should be about 1/2". You will make a total of six 90 degree bends. Be careful about squeezing the wire too much with the pliers; they will damage the heat shrink around the tubing. Put a couple of layers of tape around the jaws of the pliers, if that helps.