Oh my goodness Vickie, a designer's notebook can be an invaluable tool!
My notebook has all types of formulations such as: how long to make a frame bundle for a certain sized stone, and where to make the wraps; what length of wire to use for certain sized bracelet designs; sketches and doodles of links and connections I make once for a particular design that I may wish to recreate, but may forget once the item is sold and I don't have it to look at; etc.
I also use my notebook to document new designs as I work them out, so I can remember what I did when I create a pattern. Sometimes I see a photograph of anything, from a decorated cake to a wedding gown, and I get an idea, so I cut the picture out and tape it in my book for inspiration. Certain lines in architecture or a cast iron gate; anything that sparks an idea gets sketched.
You may be interested to read this article: Inspiration Comes From Everywhere and Every Thing!
Answer contributed by Dale "Cougar" Armstrong