For stronger design patents – less detail can give you broader coverage, so consider turning some solid lines into broken lines.
On the surface, design patents – a patent that covers the ornamental appearance of an article of manufacture, seem simple. File multiple drawings showing your design from multiple angles – often all six sides of an imaginary cube, as well as in perspective. If (under a famous court case called the Egyptian Goddess test), an ordinary observer (familiar with the prior art designs of similar products) will confuse someone else’s product with the patented design, then there is infringement.
This raises interesting questions of pattern recognition. The problem is often explained by analogy to the Cheshire Cat from Alice in Wonderland. How much of the cat do you need to see in order to identify it as a Cheshire Cat?
In a design patent, the parts that are required are shown in solid lines, and the optional parts are shown in broken lines. As more and more solid lines are turned into broken lines, the design becomes more general, but of course at some point, the design then becomes too general to be unique or even recognizable. See “A Guide to Filing A Design Patent Application” for more information.
When broad coverage of a design is desired, consider filing multiple versions (or alternatively continuations) of a design patent. Narrower but safer versions can have more solid lines; in riskier but broader versions, replace the less essential solid lines with broken lines. Perhaps a subset or outline of your product is distinct enough to warrant design patent protection? If you think that your design may have multiple distinct sections, consider putting in broken lines to show these sections in the initial filing, since the USPTO won’t let you do it later.
Compared to utility patents, design patents are relatively inexpensive to file, and relatively easy to get. However again, the design patent is only for the artistic and non-functional aspects of the design. Design patents now have a 15 year lifetime, and no maintenance fees are required.
Many countries also accept international design patents as well, but you usually only have six months to file.
A few more tips — design patent examiners have a well-developed ability to detect inconsistencies between drawings and/or ambiguity in drawings. Problems can often be avoided by first making good quality 3D CAD files, and then making these 3D CAD files available to the patent attorney.