Did you ever have a Slinky? Those loose springs which “walk” downstairs. They've been around since the 1940s and, like Jacob's Ladders, they'll likely always be around.
These infinity rings are in the same family of stims as the Slinky with one important difference – you don't need stairs for them! What starts as a short stack of thin metal rings pops up into a big fat springy donut. Cool. But the fun hasn't started yet... thread your hand through the center “hole” of your the donut, then lift your arm and...
This is like a Slinky that flows up and down your arm, or even your leg (if you're small enough), in fact, anything roughly cylindrical that'll comfortably fit through the “donut hole”
It's fascinating, it's visually stimulating, it's motion is mesmerizing and you know what – it FEELS nice when it's undulating up and down your arms. Definitely not a stim for out in public, but oh so much fun at home..