Who knows what this is???

[Mfilippo55]

I think I bought it 7 or so years ago when I was photographing a lot of artwork for eBay.

[Dan Fromm]

I think I bought it 7 or so years ago when I was photographing a lot of artwork for eBay.

It is a 2 axis focusing rail.

[benjiboy]

It's a centrifugal scrunge pump

[Mfilippo55]

Yep, that was my guess also!

[Mfilippo55]

For copying, like with a copy stand?

[AgX]

see here:

http://www.kaiser-fototechnik.de/en/...ge.asp?nr=5534

For exact camera positioning for close-up, macrophotography and copying. Two positioning scales are perpendicular to one another. Setting range each 95 mm (3.7 in.). Prismatic precision guideways with micro adjustment across helical gear rack-and-pinion assemblies complete with lock screws and dials calibrated in millimeters. (Kaiser)

However your version has mounted in addition:
-) a rectangular gusset with 1/4" screw at base mount
-) a rectangular gusset fitting both racks

yielding a further 90° off-set in both cases.

[fotch]

It is a Thing! You mount a camera on one end and well, a, something else on the other.

[Mfilippo55]

That's almost what I've been calling it... a thingy.

[Jim Jones]

It appears to be for precisely positioning a camera for macro-photography. In the heyday of TLRs, a similar devise was used in macro-photography to reposition the taking lens in the same position as the focusing lens.

[desertratt]

It's a rudder for a duck.