What is a 3D printer?

If you enter a drawing to the computer one object appears as drawings. You think it is possible? Sounds impossible, but there is a thing that makes possible. It is 3D printer! 3D printer is a thing which can make three-dimensional products after some process(modeling, printing and  finishing.) 3D printer’s principle is similar to inkjet printer but unlike the inkjet only prints letters you can make three-dimensional products through up-down moving. In fact, 3D printer was invented by enterprise