All that is required to file a patent application is a description of the invention detailing those items which are novel and useful. Except for a few special cases, a prototype or working model of the invention is not required by the U.S. PTO. Formal drawings will be required at some point in the application process, but they are not usually necessary in order to file an application and, thereby, to establish a filing date.
Just as any individual may act as his or her own counsel (pro se) before a court of law in the U.S., so may any inventor file an application for patent protection for his or her own invention. Just as it may be less than wise to be your own attorney, however, it is probably also a better idea to have someone else champion your patent application. This is probably more advisable in connection with the prosecution or defense of patents than in most other areas of law practice, because patent law places great importance on the correct use of language and use of exactly the correct language. The nature of a protected claim can turn on the precise meaning of a word or the wording of a phrase.