The following videos show metal part machining with multi-axis, numerical controlled machine tools (such as Mazak Integrex). The machining tool can be used to make objects with smooth, curved shapes as well as complex geometries.
This video shows a CNC (computer numerical controlled) machine tool making a propeller.
Waterjet can be used to cut thick mechanical parts to form machine parts such as turbines.
Laser cutting machining process is used to cut metal pieces with vertical walls.
Rapid prototyping can be done with 3D lithography, laser printing, and many methods. Below is a collection of interesting techniques.
3D printing with a machine called Objet