Although it's hard to tell in my rather bland-looking example, users of the site can basically choose from several colors for each of the parts, and the left and right pieces don't necessarily have to match. There are also pre-configured combinations and even a random generator if you're feeling lucky.
The earphones can be purchased for ¥3600 in Japan.
DESIGN YOUR HEADPHONES | KOTORI
Have fun, and feel free to post your creations!