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.