My non-designed object is the lowly DOOR. Yes, the door.
The object you open to enter or exit a room or building. Not only are doors functional,
they can also be beautiful. .

images courtesy of John C. Hutchens,  Pia – Artemisia1975,  John Kroll

Doors come in all shapes, sizes, and manner of construction. There are cool coffee table books on doors from around the globe. There is even something called, "The Norman Doors", where User Experience expert, Don Norman, examines why some doors are not very user-friendly and drive us crazy. Check out this cool video.