As with many other DIY stylus creations, you'll need conductive foam for the tip. (It can sometimes be found in gadget packaging, keyboards or TV remote controls). Other than that, you just need the copper wire to wrap around the chopstick so you're connected to the phone. And, of course, a chopstick. You know where to get those.
Hit up the link below for the instructions from hixair, who says using the chopstick stylus is like using a paintbrush.
DIY iPad Stylus! [Instructables]