The fact that you are not a draftsman or have even no idea of how drawings are made, need not deter you from making sketches that will be understood. A sketch or drawing is a representation more or less correct of the imaginary object in your brain. Drawings or sketches are the easiest kind of writing. They are picture writing, usually the first mode of writing employed by primitive people, and any man who has the intelligence to invent, no doubt has sufficient ability to make some kind of sketches with pencil on paper of the pictures he conceives in his brain.

In making your sketch, remember that nearly every object has many sides to it, and your sketch is to impart a conception of the shape and form of that object to somebody else who has no knowledge of it, and must necessarily get his ideas from your sketches as he cannot look inside of your brain; therefore make as many sketches of your object as there are sides to it, and mark them, front, side, back, top and bottom, and every separate piece, 1, 2, 3, etc.

Write up explanations or specifications of the same. You can learn how to do that by reading standard works on applied mechanics.