What 3D printer filament is: the feedstock, the families, and the sizes

The main filament families

Most desktop printing comes down to five families. Each one picks a different balance of how easy it is to print, how strong it stays, and how much heat it can take.

How filament is made

A producer melts plastic pellets, pushes the melt through a hole that sets the diameter, and winds the cooled strand onto a spool. The two common sizes are 1.75 millimeters, the desktop standard, and 2.85 millimeters, used on some older machines. The printer’s extruder grips the strand and feeds it into a heated nozzle, where it melts and is laid down along a toolpath.

Choosing by what the part has to survive

The right family depends on the job. PLA is the easy default for prototypes, miniatures, and indoor decor. PETG adds toughness and handles damp sheltered use. ABS and ASA take heat and sun but need an enclosed, vented printer. TPU bends instead of breaking. Nylon brings strength but pulls moisture and wants drying. Start with PLA, then move when a part needs more than ease.

For a deeper material dive, the PLA guide and PETG guide cover the two most common families, and the filament glossary entry explains how a printer actually uses the strand.