A personal project that we've been working on for the past couple of months. Its a replacement cap for a Bic cristal pen that works as stylus for capacitive screens.
Most of the time was spend on getting the tolerances of the 3D print right. Also making the right coating for the tip required a lot of trial and error.
It is 3D printed (SLS) at Solid Concepts in carbon filled nylon, which is conductive enough to work perfectly as a stylus.

More info at: www.lab02.org