Sometimes part of your body other than just your hands need to fidget (or be massaged).  These two simple and functional designs hopefully help stimulate your feet and mind during those longer work days.

Provided in 3MF and Fusion360 files for people who want to customize.  

Built to be tough and take a beating, these print great in PLA but if you're going to put lots of weight on it, I recommend at least 4-5 walls and 4-5 top/bottom surfaces to bear the weight.