This bridge is from the K'nex Building Bridges set, which progressively explores a dozen bridge designs. Some of the later ones are more impressive, but I was more interested in making a stereograph than a bridge.
If you look at these images with a stereo viewer or by merging the two images with a free-viewing technique, it will be in 3D, ala the View-Master many of us enjoyed as kids, and some of us still enjoy.
No big whoopee, but this is my absolutely first stereo pair, so I am kind of pleased.
I used my regular camera, moving it to the side between exposures to create the divergent points of view.
The Manfrotto Modopocket may be my favorite camera accessory. For the stereograph (3D image pair), I put a metal ruler with a non-slip cork back on the table with the ends weighted, put the Modopocket against the ruler, and displaced it to the side along the ruler to create spaced parallel images for manipulating into a stereo pair.
For more on 3D photography, you might start with DrT's website.
And another way to enhance what was already good block play.
Addendum [12/24/09] - In my confusion, I had originally referred to the technique for viewing my image pair as using the "cross-eyed technique," which Dr T was kind enough to gently point out was wrong, since that requires a reversed stereo pair. I have corrected both the terminology and the link above.