1. Make pattern as image displays, you can download the image in http://3dcarving.blogspot.com/2012/01/blog-post.html#more, download the third image.
2. Pull the pattern up.
3. Offset the surface.
4. Connect all the lines.
5. Make additional lines in the middle of the pattern with Line Tool.
6. Select the blue lines then move them down using Move Tool.
7. Push down the surfaces in the middle.
8. Select the blue lines then move them up with Move Tool.
9. Triple click on the object then use Subdivide & Smooth (Artisan plugin) twice for smooth result.