What type of machine features two wheels and is capable of making a double curve?

The English wheel is designed specifically for shaping and forming metal into complex curves. Its distinct feature of having two wheels allows for the manipulation of metal sheets to create double curves, which is essential for applications in aircraft fuselage and body panels where aerodynamic shapes are required. The larger wheel provides a smooth surface to shape against, while a smaller wheel is used to guide the metal, enabling artisans to stretch and form the material accurately.

In contrast, other machines listed serve different purposes. A press brake is used primarily for bending metal along a straight axis and does not accommodate the creation of double curves. A bending roll is designed to roll metal into cylindrical shapes and is not utilized for intricate curves as seen in the English wheel's capabilities. The band saw, on the other hand, is a cutting tool that excels at cutting through materials rather than shaping or forming them.

Given the need for double curvature in metalworking, the English wheel stands out as the appropriate choice due to its specific design and functionality.