I have been thinking about how I could build something, but have been traveling for quite some time, and just didn't have the right materials on hand until recently. After avoiding doing the dishes for a couple weeks, things finally got serious and I decided to give this idea some thought again. Serendipitously, this time, there was a box of K'NEX sitting in front of me, so I got to work.
Previously when building mousetrap cars I had constructed a "mousetrap dock" that made it easy to design and redesign the cars without having to change the drive mechanism. This was a great place to start, but it didn't fit my iPhone (which isn't quite as thin as a mousetrap).
All I had to do now was build something that would sit on my head, strong enough to prevent the iPhone from falling off into the dishwater. You may need to customize this design for yourself, depending on your head size, but the following works well for me.
video of how the head set works!