What Is a 3D Printer? How It Works and What It's For

A model drawn on a computer becomes an object you can hold a few hours later. That is essentially what a 3D printer does. This article explains how it works, which types exist, what materials it prints with and what to look at when choosing your first printer.

What is a 3D printer?

A 3D printer is a machine that turns a three-dimensional model prepared on a computer into a physical object by adding material one layer at a time. It can work with plastic, resin, nylon powder and even metal. On the desktop machines used in homes and small workshops, the most common material is filament, a plastic strand wound on a spool.

Traditional manufacturing, such as milling and turning, carves a part out of a solid block. In 3D printing, material is added only where it is needed. This approach is called additive manufacturing, and in everyday speech "3D printing" refers to all of these technologies.

The practical result is that you can make a single part without molds or special tooling, and you can print hollow or organic shapes in one go.

How does a 3D printer work?

Whatever the technology, a print goes through the same five steps:

1. Prepare the model. The object is drawn in a CAD program or downloaded as a ready-made file. Files are usually in .stl or .3mf format.
2. Slice the model. Software called a slicer cuts the model into thin horizontal layers. Layer thickness, infill, print speed and temperature are all set here.
3. Generate G-code. The slicer produces a list of coordinates and commands (G-code) that the printer understands. The file reaches the printer by USB stick, cable or network.
4. Print. The printer heats up to the requested temperature and builds the layers from bottom to top.
5. Post-process. The part is removed from the bed, supports are taken off, and it is sanded or painted if needed.

The drawing at the top of the page shows this flow with a vase: the model is sliced, then the printer adds the layers from the bottom up.

Print quality does not depend on the printer alone. The same model can turn out very differently with different slicer settings.

Types of 3D printers

Three main technologies stand out. Each uses a different material and suits different jobs.

For a closer comparison of the two common types, see FDM vs resin 3D printers.

The vast majority of printers used at home and in small workshops are FDM. They are relatively cheap, the material is easy to find and they are the easiest type to maintain. Resin printers are excellent at fine detail, but liquid resin, washing and curing add extra work and extra safety precautions. SLS machines are used mostly in professional production.

Parts of an FDM printer

Most beginners start with an FDM printer, so knowing its basic parts will also help you when you go looking for the cause of a fault later.

• Filament and spool: The plastic strand, most commonly 1.75 mm in diameter. It is fed from the spool to the printer.
• Extruder: A gear drives the filament into the hotend.
• Hotend and nozzle: The heater block melts the filament, and the nozzle (the tip) lays the melted plastic down as a thin line. Most printers use a 0.4 mm nozzle.
• Print bed: The surface the first layer sticks to. Many models heat it.
• Motion system: Stepper motors move the axes (X, Y and Z) using belts, lead screws or rails. Which axis carries which part depends on the model.
• Control board and screen: The electronics that manage temperatures, motors and G-code.

Filament types

On an FDM printer, the choice of material determines how strong the part is and how hard the print will be.

These values are approximate ranges. Every brand prints its recommended temperatures on the box or spool, so use those first.

If you are just starting, PLA is the smartest choice. It prints easily and lets you learn how settings come together. PLA does soften with heat, though; PLA parts left in a closed car in summer can change shape. For parts used outdoors or in a hot place, PETG or ASA/ABS are usually preferred. There is a detailed comparison in PLA vs PETG vs ABS.

What is a 3D printer used for?

• Prototyping: One of the fastest ways to try a product idea in physical form.
• Spare parts and repairs: Broken plastic holders, knobs and clips can be printed again.
• Organizers: Drawer dividers, cable holders and shelf brackets.
• Hobbies and games: Figures, miniatures, costume accessories and tabletop game pieces.
• Education: Used in schools and workshops to teach design and engineering.
• Architectural models and product design: Scale models in a short time.
• Medicine and dentistry: Models, guides and devices made on professional, certified systems. Parts printed at home are not suitable for medical use.

Limits of 3D printing

The technology is versatile, but expectations need to be realistic.

• Time: A small part takes from half an hour to a few hours, and a large part can take more than a day.
• Direction-dependent strength: The bond between layers is weaker than the layer itself, so a part splits more easily along the layers.
• Surface: Layer lines are visible on FDM prints. For a smooth finish you need sanding, filler or a resin printer.
• Size: Entry-level printers usually have a build volume of about 200–256 mm per side. Larger parts are split and joined.
• Supports and finishing: Overhanging areas need support structures that are printed and then removed.
• Material: Plastic parts are not as strong as metal. Parts that carry heavy loads need careful design.

A short history

The roots of 3D printing go back to the 1980s. Chuck Hull developed stereolithography (SLA), which cures liquid resin with light, in 1984, received the patent in 1986 and founded 3D Systems. In the late 1980s Scott Crump developed FDM, today's most common method, and founded Stratasys.

The RepRap project, started by Adrian Bowyer in 2005, aimed for an open-source printer that could print most of its own parts. As the FDM patents expired in the late 2000s and open-source designs spread, desktop printers quickly got cheaper and moved into homes.

What to look for in your first printer

This article does not recommend a specific model, but we can tell you which questions to ask. For a more detailed list, read how to choose a 3D printer.

• What you will print: Small figures, boxes and brackets, or large parts? Pick the build volume accordingly.
• Automatic bed leveling: Most first-layer problems come from bed leveling. This feature makes life easier for a beginner.
• An enclosed or enclosable body: Useful for materials like ABS, and for noise and safety.
• Community and spare parts: Easy availability of consumables such as nozzles, hotends and build plates, and plenty of online help, is a real advantage.
• Slicer support: Check that it works with common software such as Cura, PrusaSlicer, OrcaSlicer or Bambu Studio.
• Total cost: Add filament, spare nozzles, a scraper and cleaning tools to the price of the printer.

Safety and environment

• Burn risk: The hotend can go above 200 °C and the bed up to 100 °C. Do not touch them during a print or right after.
• Fire safety: Do not leave the printer unattended if you can avoid it. The risk is higher with older or low-quality kits that have no thermal protection, so check for this feature before buying. A smoke detector nearby is a good precaution.
• Ventilation: ABS and ASA prints and resin printers give off a noticeable smell. Do this work in a ventilated space.
• Resin safety: Wear gloves and eye protection, do not pour resin waste down the drain and read the manufacturer's safety data sheet.
• Food contact: Gaps between layers can harbor bacteria, so printed parts are not recommended where they touch food directly.

A simple way to start

1. Set up the printer and level the bed.
2. Buy PLA as your first filament.
3. Download a small, simple ready-made model. Printables, MakerWorld and Thingiverse are commonly used sites for this.
4. Use the slicer's ready-made profile. Do not fiddle with settings on the first print.
5. Watch the first print. A well-stuck first layer decides the rest of the print. If something goes wrong, see first layer not sticking.
6. Once you are comfortable, try drawing your own simple models in a free browser-based program such as Tinkercad.

Frequently asked questions

How long does a 3D printer take to print?

It depends on the model's size, layer height, infill and print speed. A small part can print in half an hour to a few hours, while a large, dense part can take more than a day.

What materials do 3D printers use?

Desktop FDM printers use plastic filaments such as PLA, PETG, ABS, ASA and TPU. Resin printers use photopolymer resin. Nylon and metal powders are processed on industrial machines.

What is the best filament for beginners?

PLA. It prints easily at a low temperature, is less prone to warping and does not need an enclosure.

Are 3D printers harmful to health?

Under normal conditions, printing PLA in a ventilated space is low risk. Materials like ABS, ASA and resin can give off smelly, irritating fumes, so ventilation and protective equipment matter. Hot parts carry a burn risk and unattended operation carries a fire risk.

Where do I find 3D models, and how do I draw my own?

For ready-made models, look at sharing sites such as Printables, MakerWorld and Thingiverse. To draw your own, Tinkercad is easy for beginners, and later you can move on to programs like Fusion, FreeCAD or Blender. Do not forget to check a file's license.