One may have a product with a unique or unusual look. A question may arise as to whether the product may be protected by a design patent or copyright or both.
Design Patent
A design patent protects the way a product looks. The protected design includes surface ornamentation or the configuration/shape of the product or both.
For example, a cup may have an unusual shape or surface engraving which can make it eligible for design patent protection.
However, the design must be "primarily ornamental, and not merely a by-product of functional or mechanical considerations of the product.
The term of a patent is 15 years. It cannot be renewed. Therefore, once a design patent expires, anyone can copy the design without patent infringement liability.
If one desires foreign design patent protection outside of the US, one can claim the "benefit" of the earlier filing date of a US design patent application if the foreign design patent application is filed within six months of the US filing.
To establish design patent infringement, one must be able to prove that an ordinary observer would think that the accused design is substantially the same as the patented design.
Copyright
Copyright protects original works of authorship. People often associate copyright with sculptures, novels, movies, and paintings.
However, like the cup above, if it has a unique shape or surface engraving, the cup shape my be protected by copyright. And the surface engraving may be separately copyrighted.
The term of a copyright registration varies. But in general, the term is for the life of the author plus 70 years.
For recent copyright registrations, there is no renewal.
To prove copyright infringement, one must prove copying. This means that the accused infringer had access to the copyrighted work, and that the copyrighted work and the accused work are substantially similar.
Summary
Patent and copyright offer different protections for a unique looking product. Obtaining both patent and copyright protection can be advantageous.