A ball peen hammer.
Cold forming sheet metal with a hammer.
You also have to grasp the fact that you can reduce the area of sheet metal by thickening it.
The tokyo based goldsmith yutaka nagai demonstrates how to hammer down a gold ingot to form a sheet.
Something to cut the metal like sheet metal shears or tin snips.
Hammer forming is one of the oldest simplest and least expensive ways to shape sheet metal.
Something like a sharpie to mark on the sheet metal.
You have to adjust your mind to the concept that when you hammer on sheet metal with a steel hammer onto a steel dolly or anvil that you will expand or increase the surface area by thinning the metal.
This is a handy metal fabrication technique you need to learn.
And some sand paper to smooth out the edges.
How can you go about shaping metal with hand tools alone.
You may want a smaller hammer for small shapes or a larger hammer for larger shapes.