A Mechanism (https://getmechanism.com) grip for the Stadia controller. I found some issues with the original design, so I made some tweaks and widened the band. It still wants to slide on the controller, so I recommend adding some adhesive. Double-sided carpet tape seems to work well.

Admittedly, it's not a great model for FDM printing, but it can be done. The print in the photos was done in SLS nylon.