I have the structure to on my early iPad Pro 12.9. I have the bracket attached and seem to have it even with the edge of the iPad. Two things that I have noticed are that the lenses for the scanner don’t seem to be aligned with the lens for the camera. The other is that whenever I try to calibrate it seems like there is a misalignment in that I can align an edge At the top of the screen but at the same time and edge on the bottom of the screen won’t be aligned. Even though that would be a vertical line on a building or something.
That seems to be something that would happen if the lenses are in direct horizontal alignment with each other.
I need to kind a shimmy up the sensor in its holder about two or 3 mm to get the iPad and sensor lenses seemingly inline.
At least now I am getting through the calibration step. But my scans are complete crap.