Fascinating - particularly when you realize that this tech is about a century and a half old. Really, improvements in the cost of precision are about the only change in that time - it's much faster and cheaper for a craftsman to the small-detail work which allows a box of this complexity to be made. Could have been done a century ago, but it would have taken a master craftsman a year or more to do the work. Now, it can be done by a well-trained technician (working from a master craftsman's direction) in several hours to a couple of days.
But it's deeply interesting stuff.