The rubber caps on the steel joysticks of my Xbox Elite 2 Controller broke off over time due to wear. These rubber caps fit over the end of the steel joystick to replace it. They have a textured top for grip against your thumb.

They're a tight fit and I had to work them into place properly with some needle nose pliers. 

Printed with TPU at 15% infill. They wouldn't get over the end of the joystick properly with any other filament.