© 2010 IconMoon & TheDesignInspiration.com
Firstly, I built some simple models and rendered them in 3ds Max, just to get the correct perspective and decide the shape before going on with Photoshop.
The Line Art
After the overall feeling is confirmed, I started to make the line-art in Photoshop before the final shading.
This icon set is released for free, can be used in both personal and commercial projects.