Optimal cylindrical can (h=2R): V=2piR^3, S=6piR^2
Cube with the same volume: V=x^3->x=((2pi)^(1/3))R, hence S=6x^2=6((2pi)^(2/3))*R^2
That's ~8.4% more sheet metal. If you don't mind contents swirling inside the can cylinders are the way to go.
Optimal cylindrical can (h=2R): V=2piR^3, S=6piR^2
Cube with the same volume: V=x^3->x=((2pi)^(1/3))R, hence S=6x^2=6((2pi)^(2/3))*R^2
That's ~8.4% more sheet metal. If you don't mind contents swirling inside the can cylinders are the way to go.