What is an “Expression of an idea” and “Fixed in a Tangible Medium?”
Although the smartphone is a “tangible medium” according to the definition of copyright, it is not an “expression of an idea” – it is a useful and functional object. Now, if you take that same smartphone object, and transfer it to an art gallery, and display it as a work of art, that smartphone object becomes the expression of an idea set in a tangible medium. The expression of the idea, being the artist’s intention – the artist’s purpose in creating that work. If we assume that the work is called “post post post modernism”; that would be the expression. The tangible medium is then the smartphone. That conversion is enough to change the nature of the smartphone, from a useful object to the expression of an idea. That work would be protected by copyright. But only the work, and not the useful elements of the smartphone that inspired the work.
To conclude, it should be reiterated that the design object or process, being useful, is governed by the patent regime. However, preliminary expressions of that object (sketches, models, notes) to the extent that they are expressions of ideas, belong to the copyright regime; but they only protect that expression, and not the design object.
In addition, artistic expressions set in the final design object, which have no functional component, such as a drawing on a can of soda or the label of a soap package, are governed by copyright. Then in that case there would be an object of design functional components protected by patents, and expressive components protected by copyright.