Magic eye tube

I was hoping this would be some new fangled way of viewing magic eye images mapped onto the inside of a tube through something like polar coordinates and viewed like a kaleidoscope. I was disappointed.

I remember playing with my father's collection of tape recorders when I was young and one of them had such a "cat's eye". Maybe that's where my love for glowing phosphors started.

I remember as a kid some device had one of these, but I can't for the life of me remember what it was.

Related:

The Magic-Eye Tuning Indicator, W G Morley, The Radio Constructor, March & April, 1969:

https://www.r-type.org/articles/art-137.htm