Practical Metal Plate Work by Paul Hasluck
Chapters include the materials used; geometrical construction of plane figures; geometrical construction and development of solid figures; tool and appliances used; soldering and brazing; tinning, re-tinning, and galvanizing; examples of practical metal plate work; and examples of practical pattern drawing.
Remember this is same man who gave us the incredible book Metal Working: Tools, Materials, and Processes for the Handyman; that book provides an excellent chapter on sheet metal, but this provides much more information, much more detail.
You'll see all the stakes, hammers, punches, groovers, and shears you could want. You'll also see a burring machine (or Jenny), bench standards, tube bend rollers (slip roll), a folding machine (brake), a bottom-closing machine, a paning down machine and much more.
You'll be shown how to make trays and bread pans. If you can do that successfully, you're on your way to building tools boxes of your own design. More difficult is the fabrication of a sauce pan, a ship's ventilator (air scoop), an oval bottom tea kettle and more. Once you have completed these lessons, you should be able to fabricate almost anything.
To get from flat sheet metal to a water tight three dimensional container requires a good pattern. You'll be shown all the necessary geometry to lay out the pattern without heavy theory.