Regarding one point of post #47
". . . apparently the PS-6 doesn't have an integral bellows. What was Nikon thinking?"
The Nikon PS-6 has an integral bellows shade to keep room light from interfering with film or slide copying. To open it, you’d grasp the rearmost frame and pull rearward to defeat the two magnet latches at the sides that normally keep the bellows shade closed. It opens most easily by prying open one side at a time.
You can see this in the following video at the 1:15 time.
Nikon PS-6 slide negative copy and lightroom editing - YouTube
Here’s a video about using the PB-6 bellows unit.