The volume of metal used in making 3m (300cm) of the pipe can be calculated by finding the difference between the volume of the outer cylinder and the volume of the inner cylinder. 

The internal radius of the pipe is 10cm, so the external radius is \(10 + 3 = 13\)cm. 

The volume of the outer cylinder is given by the formula \(V = \pi r^2h\), where \(r\) is the radius and \(h\) is the height. 

Substituting the values of \(r = 13\)cm and \(h = 300\)cm, we get \(V = \pi (13^2)(300) = 50700\pi cm^3\). 

The volume of the inner cylinder is given by the same formula, with \(r = 10\)cm and \(h = 300\)cm, so \(V = \pi (10^2)(300) = 30000\pi cm^3\). 

Therefore, the volume of metal used in making 3m of the pipe is \(50700\pi - 30000\pi = 20700\pi cm^3\).