The Big Question—What is 3D Printing? - 3D Printing: Build your Own 3D Printer and Print your own 3D Objects - page 8

Note
Not all 3D printers use plastic. You'll learn about some other types of
3D printers later in the topic that use different methods and materials,
but for the purposes of this topic, I'll be covering those kinds of printers
that melt plastic to a liquid form and deposit (print) that liquid plastic
on a surface so that it can cool and harden.
Solid to Liquid
Plastic is somewhat of a vague term because there are many types of plastics. One
type might be much harder to twist or break, whereas another might require a high-
er temperature before it begins to melt. I talk about the various types of plastic
used with 3D printers later in the topic, but for now I just want you to understand
that before a 3D printer can actually “print” a 3D object, it must melt that plastic.
To do this, most 3D printers use plastic filament. Plastic filament is nothing more
than a very thin strand of plastic that typically comes in a wrapped bundle like the
one shown in Figure 1.5 .