3D printing

3D printing (also known as additive manufacturing) is the computer-automated construction of a three-dimensional physical object from a digital 3D model, typically done layer by layer. 3D printing is an umbrella term for many different technologies that work by this principle. These technologies have been widely adopted by the manufacturing industry, researchers and artists.

3D printers are often used by makers, being a tool for both functional and decorative objects. Desktop machines are available for as little as a few hundred dollars, making them an affordable option to bring ideas into reality.

Makers use them for a variety of things, such as to create personalized objects, single-purpose tools or for rapid prototyping. While 3D printing can be done with a variety of materials (such as metal or clay), the material that most makers will use is some form of plastic polymer, due to their low cost and wide variety of properties.

Benefits of 3D printing

Low-cost plastic objects

A great benefit to 3D printing is its relative low cost compared to off-the-shelf items, whether it be spare parts, gizmos, toys or collectibles. Often a desired object cannot be purchased through traditional modes at all, so self-manufacturing is the only option.

Easy to customize

Because virtual models are relatively easy to alter, 3D printing is often used to create custom, unique objects. This can be anything from a Christmas tree ornament with your parents' names on it, to a splint fitted perfectly to a patient's wrist, or even a small statue of your 3D scanned self.

Easy to replicate

While printing a 3D model for the first time will often take some experimentation, once you get a successful result, recreating that result will be significantly easier. That means if an object you printed in the past breaks, you can quickly make a replica without a big investment of time or money. In a more professional context, this also makes 3D printing a great option for low-volume manufacturing, used by many small businesses today.

Rapid prototyping

One of the unique benefits of 3D printing is that it allows for making cheap prototypes, which can then be tested and modified quickly as needed. This can be applied to mechanical projects, electronics, architectural models, artistic works etc.

Choosing your 3D printing method

For makers, the two most readily available forms of 3D printing are material extrusion and vat polymerization. For a full list, see List of 3D printing technologies.

Fused filament fabrication

In fused filament fabrication (also FFF or FDM), the material is loaded into the 3D printer and pushed through a hot nozzle. The melted plastic is deposited this way onto the build platform as a very thin thread, where it solidifies by cooling. The nozzle continues placing the filament like this, tracing out the pattern of the first layer onto the build plate. After the first layer is complete, the print head moves up one layer height, and starts building the next layer on top of the first one. This continues until the whole object is constructed.

Material extrusion devices are the most commonly found type of 3D printer in the world, given the low cost of the machines and the material. The concept is relatively simple to understand, although troubleshooting problems can prove difficult, as there are many moving parts involved.

FFF 3D printing is great for making strong, big or functional parts, and there is a great variety of materials available, such as flexible or weather-resistant ones. On the other hand, it can often fall short when making aesthetic pieces. Filament prints tend to have a cheap "plastic-y" feel, and layer lines are usually clearly visible on their surface. These qualities can be fixed with post-processing.

Vat polymerization

In vat polymerization (also stereolithography or SLA), a liquid resin is solidified by into an object one layer at a time. A UV light is pointed at a vat of resin, and wherever the UV light hits the vat, the liquid resin turns solid. This is called "curing" the resin, and the printer makes sure the resin is only cured where it needs to, on each layer. Once a layer is done, the printer moves on to the next one, fusing all of them together into a 3D object.

Vat polymerization results in a good surface finish, but is more limited in size, requires post-processing and the handling of irritant chemicals. It is usually a more costly investment than filament printing, although low-cost hobbyist machines are available on the market.

Due to the finished parts' smooth and detailed look, but relative brittleness, it is strongly preferred by those who are printing aesthetic parts (eg. statues and miniatures) over those making functional parts.

Steps of 3D printing

This is a short summary of the 3D printing process in practice.^[1] For full guides, see How to do material extrusion (FDM printing) and How to do vat polymerization (SLA printing).

A 3D model is necessary for 3D printing. These can be created from scratch using CAD software, but it's best to start out with a few models readily available online.
The 3D model is loaded into a "slicer" program. The slicer cuts the 3D shape into 2D slices, which become instructions for the printer. Print parameters such as temperature, layer height etc. are set. If support structures are needed, these are generated as well.
The instructions are transferred to the 3D printer through a USB drive, WiFi or some other method.
The printer is prepared. This means it is well-calibrated, enough raw materials (filament, resin etc.) have been loaded, and it is heated to the correct temperature.
Printing can begin. The 3D printer creates the object autonomously, without the need for human supervision or interference. This process usually takes a number of hours or even days.
The finished result is separated from the build platform, any supports are removed from it, and any necessary post-processing is carried out.