My dad has some these. There was a doodad for kids in the 70s which did more or less the same thing called the 'viewmaster' -it even had cartridges for 3-d vie

My dad has some these. There was a doodad for kids in the 70s which did more or less the same thing called the 'viewmaster' -it even had cartridges for 3-d views of stuff like Space-1999. They still sell it on Amazon.