Many Kohler showerheads have a small, stiff knob for switching water flow between the fixed head and handheld sprayer. My wife was finding this knob difficult to impossible to turn, so I created this lever knob that pushes over the Kohler knob, giving much additional leverage.

I created this in Tinkercad - you can “tinker” it yourself at https://www.tinkercad.com/things/40qQ1GVMDXI-kohler-handle

I suggest printing this in PETG.