Documentation
Write a full description of the invention and make some sketches to show how it works. Some pointers to preparing this information are below.
In most cases, an invention is made to solve a problem. Explain what the problem is.
Explain how your invention solves this problem.
Have other people tried to solve the same problem? If so, describe those other attempts and why they do not work (or not as well as your solution).
Describe in detail how your invention works. Some sketches will probably be useful in doing this.
You will probably have devised some alternative ways of using parts, or the whole, of your invention (eg using either compressed air or a spring to push one component in a certain direction). Write down all the alternatives that you have thought of.
If you have done a search, make some comments on what you found in your search.