When you need to cut a curve in a thin steel plate, the tool must follow a curved line with a narrow, capable blade and respond predictably as you guide it. A jigsaw fits that need well. With a proper metal-cutting blade (bi-metal or high-speed steel) and a controlled feed, it can trace tight radii and produce cleaner curved cuts in a 5 mm plate much more easily than a manual hacksaw, which is slow and tedious for curves. A band saw is excellent for curves too, but typical metal band saws are geared toward larger or thicker work or require a dedicated machine setup, making them less convenient for small curved shapes in thin plate. A circular saw lacks suitability for cutting metal cleanly without specialized blades and precautions, and it doesn’t handle tight curves as smoothly. So, the jigsaw is the best-fit choice for curved cuts in this thickness of steel.