Classic Fisher Price: Rock-a-Stack
Fisher Price has produced over 40 million of these since 1960. They are still produced with a slightly different design for the "donuts" and base. The newer version I have has a few less "donuts." I am pretty sure every child of the last 50 years has played with one. And it has a wiki entry . The rock-a-stack has made a few cameos in Pixar films- notably the Toy Story series. Besides that there is not much out there about it. But there is an entry on how to make a candy rock-a-stack . I think the one below is from the mid-1970s. rock-a-stack