I LOVED THESE. Those silly rubber "Poppers" that you'd flip inside out, place on a table, and watch it scare the crap out of you when it finally popped and righted itself. Admit it, you flinched every single time.
A kid could get lost in the story the viewfinder slides tell. There were no sounds but I often could picture how it was and how it would feel like going with my favorite cartoons on an adventure. The Viewmaster