One may argue that we are all natural designers. From very young age, we are designing: we are looking around us with a critical eye, we develop opinions about things and spaces that we like or dislike, we are dreaming about a better future, but also we experiment and make things that could make our life better in a certain respect. Look for example at the art work of this 7-year-old child. He got some new shoes recently and has made various observations about them using sketching!
He thought they were quite bulky at the front, which made them ugly and a bit uncomfortable for running. So he drew an improved version:
The drawing was only one part of the exploration. A bit of pottery magic was also needed to develop a better feel about the shoe:
I see this as a typical example of design thinking and I would say that the result is truly a piece of art!