I had this amazing toy it was a little plastic monkey on a bicycle or a wheel. It held a thing so it would be balanced, like one of those circus dumbell looking things like they had in cartoons when they were on the tightrope. You could set up a piece of string and the monkey would glide down it. The thing was you could set the string up at any height: out windows, you could do it down like the Grand Canyon. I wish I could find another one for my niece and nephew
edit kind of like this but smaller