You may need to click/enlarge the image to see the subtlety of the optical illusion. Then the question to ponder will be whether this is the result of image editing, or whether it was created by clever woodcrafting with veneer.
Photo from Erik Minnema's photostream, via.
The block on the right is tapered to the front along 3 sides until it ends up being a flat sheet of paperwood. Roughed up grain in the front is there to make it look like it's a different side when it's really the same flat surface by that point.
What gave it away for me was that some of the shadows were created by pencil.
Larger image here: www.flickr.com/photos/35739691@N05/3308876734/sizes/l/