Snappiness published a camera mode he is attempting to use with two Sony a7M2 to create a 72x24mm image using a 3d printer, and he almost succeeds, but his mirror placement ended up being a little off. At first he created a 36x48mm image by putting the cameras on the adapter sideways, but then he flipped them around to get 72x24mm. Since he was unable to get the mirrors to alight properly only one of the cameras was able to capture sharp images, but maybe we will see a new, improved adapter in the future with better mirror placement.
I captured some images from the video for closer viewing below: