Hi Nick,
I recommend books which teach the science affecting the invention. For example, if it flies, books on aerodynamics. When I teach inventing, I say, "Learn all you can about the science related to your invention". Studying patents related to your ideas is easy now that we have google patents. It's helpful to see what others have invented. Most inventions fail to reach production, so you'll see things that are not for sale.
Regarding making prototypes, 3D printing is used most often. But the process might not work for your invention. It's not watertight. I have a lathe and a milling machine in my garage. Neither is computer controlled. I enjoy making things on my machines.
Alan