This type of 3d printer is called a Fused Filament Fabrication (FFF) printer. That means it uses a roll of filament to print. There are many different brands, with different features and quality levels, but they mostly all work the same way. 

With few exceptions, the printer can be broken down into 3 main parts. The controller, the gantry, and the extruder. The controller reads the slicer file and controls the machine. The GANTRY is the structure that allows the printer to move around, and the EXTRUDER is where the magic happens, that's where the filament is changed into a print. 

For this project, we're going to mostly focus on the extruder. 

The top part of the extruder is called the cold end. It's called the cold end because in order to function, it must remain cool (relative to the hot end). In the cold end is a motor. That motor, based on the information in the slicer file, will precisely push filament into the hot end at the correct speed to create a beautiful print. 

Because the hot end and cold end are very close to each other, some clever engineering had to happen to stay cool. First, the cold end has cooling fins. these cooling fins increase the surface area which helps to get rid of heat energy faster. In order to help even more, a fan will blow air across the fins to cool it down even faster. If the cooling is insufficient, heat creep can cause the filament to liquify too early and jam the machine!