The Big Question—What is 3D Printing? - 3D Printing: Build your Own 3D Printer and Print your own 3D Objects - page 5

Figure 1.3 A basic example of what a 3D printer can accomplish.
And there you have it. A 3D printer can print something with length, width, and
height. But I can already hear some of you saying, “ But no matter how many times
I print that square on the same piece of paper, it's going to stay flat. This is crazy
talk!”
And you're right.
Ink is not very useful for printing solid objects.