Regardless of what you decide to do in EVE, you are going to need certain things. They can be ships to fly, modules to fit your ships with, or even the ammo for your weapons if you choose to engage in combat. The fact that EVE has an entirely player-driven economy, means that all these things need to be manufactured by someone, and that someone can and should be you. Not only could you then supply everything you would need, but you can make a sizeable fortune as well.
I would strongly advise that you do not go into manufacturing with the sole purpose of producing only what you need. In order to justify the initial time and energy needed to start, your manufacturing operation needs to be fairly large scale and needs to produce items that will sell, not just what you will use.
This chapter, much like the majority of this book, is written for solo careers. In manufacturing just as in mining and mission running, it is often much easier and quicker if these careers are undertaken...