So this test photo does actually show what this lens does. When you bend the tube a certain way, you can bend the plane of focus (which is usually perpendicular to the direction you’re pointing your camera, which is why, if you focus on things 2m away – all things 2m away will be in focus.

With this thing, you can bend this imaginary line. In this example, the pen pot (which was definitely not a tin of chocolate wafer tubes) is pretty much in focus here, whereas the light on the left is wildly out of focus, even though they are equidistant to the lens/sensor.