One of my students really likes this thingy called a “Think ‘N Roll”. It is a tool for fidgeting feet.
It can make noise so I have cautioned students that when that happens it is no longer an effective tool helping them to listen and will be put away for a time.
This is discreet, keeps kids from tipping the chair, and it is simple to add or remove. It costs $9. at School Specialty Canada. Unfortunately shipping and handling can add a chunk but I was ordering a bunch of stuff since there are some neat tools available.
The Resourceful Resource Teacher 