Nylon, a popular family of synthetic polymers used in many industrial applications, is the heavyweight champion of the 3D printing world. Compared to most other types of 3D printer filament, it ranks as the number one contender when together considering strength, flexibility, and durability. Another unique characteristic of this 3D printer filament is that you can dye it, either before or after the printing process. The negative side to this is that nylon, like PETG, is hygroscopic, meaning it absorbs moisture, so remember to store it in a cool, dry place to ensure better quality prints. In general, many grades of nylon exist, but among the most common for use as 3D printer filament.