Anyone remember these things? The old viewfinders? This one dates back to when I was a kid. My mother purchased it with a set of little slides each depicting a mystery of the rosary. We would insert the slide into the top of the viewer to see the picture, a 3-D (sort of) picture of some aspect of each mystery. I loved it. We would pass the viewer around as my family said the rosary together.
The Family Rosary. I can't say enough good things about it. But I did write a little essay about it for Catholic 365 and you can find it here.