It's a pity there is no picture. There has to be a Nikon mount for the camera and I infer from the description that it would use Nikon lenses rather than large format ones (?). I presume there are no electronic connections so everything would be manual.
I'd hazard a guess that most people likely to be interested in this would have used large format cameras in the past. If you happen to have one lying around, there's a much cheaper DIY option that
Keith Cooper explains.
Maybe I'll try that myself sometime. I have two 5x4 cameras but the wooden field camera is probably too light to hang a D3 off the back. On the monorail, I could replace the ground glass with a plate to hold the camera. Because the D3 would be displaced from the back of the monorail camera, the lenses would have to be closer than normal to the rear standard which would probably preclude using wide angles. Not high on my list of priorities to attempt, though, I must admit.
Regards,
Murray