What is 3D Printer Filament?

3D printer filament is a term used to describe the plastic that is used to create your shapes and creations by a 3D printer. The majority of desktop/consumer 3D printers use a technology called Fused Deposition Modeling (or FDM for short). FDM is a simple process where a molten material is deposited at certain locations on a build bed to form a layer. Multiple layers on top of each other form the overall desired shape. So FDM printers simply melt plastic and then extrude this plastic onto a build bed in layers. This is how a 3D printer can print any shape you want.

3D printer filament comes in a variety of shapes, colours and sizes (we shall discuss the various types later on in this guide). However, filament will always be a small strand of plastic, usually rolled onto a spool. The end of the filament is inserted into the top of the 3D printer where it is melted and extruded.

Filament is usually sold by weight. For example, you might have seen filament sold in 1kg spools. This is simply a way to quantify the amount of filament people buy. You might think it would be more sensible to sell filament by its length (and some sellers do do this) however, since many prints usually use a tiny length of filament it is easier for bulk selling to quantify it by weight.

There are two industry accepted diameters of filament: 1.75mm and 3mm (or 2.85mm). 3mm filament is much less common than 1.75mm filament due to a fewer number of 3D printers requiring 3mm filament. Furthermore, it is easy to convert a 3mm printer to use 1.75mm but not so easy to do the reverse. The result is a far greater choice of 1.75mm filament. If you have a 3mm printer and want to convert it to 1.75mm filament then see the end of this guide.

3D printing filament is always made of plastic as 3D printers require the ability to melt and solidify material. However, there are many different types of plastic used for 3D printing and some even have additives in to give them the properties of other materials such as metal and wood.