You probably touch several of these a day without thinking of their reliable function. Door knobs. Are they important things? Am I just filling this description with filler? I think you know the answer.
But spend a day noticing knobs. Shiny. Worn. Plain. Ornate. Photograph at least 4 ones with unique enough differences to define a statistical deviation. Whatever.
Example for "Doors of Perception, Opportunity… all Need Knobs":