Although many inventors believe otherwise, drafting a patent application is not an easy endeavor. Indeed, the United States Supreme Court has described a patent application as one of the most difficult legal instruments to create. There are a great many pitfalls and perils that face anyone who drafts a patent application, particularly inventors who are not intimately familiar with the patent laws and regulations that will apply.
The trick with drafting a patent application is to define anything that will work, no matter how crude, no matter how defective.
Read more here.