RE: two-short cameras into one - this might relate to trialing big lenses, etc.. It allows the mount of many kinds of cameras to an oversized, heavy lens. You can center the lens using the sliding platform on the left. The bottom black rail can be moved back and forth to balance the unit on the tripod, and of course the same can be done with the mounted camera. (not shown: another taller left platform and a Bogen strap that can be added to the lens mount.) Some might recall seeing this as an item on that auction site identified as "bunch of stuff", "don't know what it is". Other goodies irrelevant to picture making were included. It is all steel, but maybe this will help those who might want to copy it in wood.