One of the foundational tools of any real metal shop is a metal cutting band saw. This can be used for cutting large pieces down to size and even for some more precise jobs. It works by using a saw blade that is continuous circle with a blade or cutting surface on one side. It is spun at high speeds in order to grind through the metal. It's usually important to wear eye protection and use cutting fluid in order to maximize efficiency and safety will cutting metal. Some saws may require that you push the workpiece through the blade, while others have a gravity driven blade that cuts through a workpiece that has been clamped down.
Either way, this is a very efficient means of cutting through large quantities of metal with minimal manual work by hand. Once you have a metal cutting band saw, you can investigate buying more special use and esoteric tools for doing more precise and less common jobs now that you can cut your stock down to size.
Saw Band
It's important to remember that while a band saw for wood cuts through the material with teeth and blades, a band saw for metal actually grinds through the metal with some sort of abrasive which is usually silicon carbide or even diamond in some cases. In order to avoid breaking the relatively delicate blade, it's important to recognize when the blade tension is too high, and when you are putting too much pressure on or twisting the metal blade too much. The replacement band saw blades are not cheap!