How Does 3D Printing Work? A Practical Guide

3D printing has become a core tool in product development, industrial engineering, and creative design. Yet despite its widespread use, many teams still ask a fundamental question: how does 3D printing work?

This guide breaks down the principles behind 3D printing technology, explains the most common processes, and highlights how 3D printing can be used to accelerate development, reduce costs, and enable new possibilities.

Whether you’re building functional prototypes, refining a concept for a client, or evaluating options for small-batch production, understanding how 3D printing works helps you choose the right approach for your project.

What is 3D Printing?

3D printing, also known as additive manufacturing, is the process of building a part layer by layer from a digital design. Instead of cutting material away (subtractive manufacturing) or casting it into a mould, additive manufacturing deposits or solidifies material only where it is needed.

This is where the term additive comes from. The meaning of additive manufacturing is simply the act of creating objects by adding material selectively, following a digital model.

For teams looking to reduce waste, speed up prototyping, or unlock new geometries, additive manufacturing offers a modern alternative to traditional fabrication.

How Does 3D Printing Work? Step by Step

Although each 3D printing technology uses a different method to create a part, they all follow the same underlying workflow. Here is the process step by step:

1. Start with a CAD Model

Every 3D printed part begins as a 3D file created in CAD software. This model defines the exact geometry of the final component.

2. Convert the Model into Printable Layers

Slicing software prepares the file for printing by:

• Slicing the model into thin layers
• Determining toolpaths or exposure patterns
• Assigning support structures if needed
• Calculating material usage and build time

This step is crucial for ensuring the final part prints successfully.

3. Print the Part Layer by Layer

The printer builds the part according to the sliced file. Depending on the technology, it may:

• Extrude melted thermoplastic
• Fuse powdered polymers with heat
• Cure liquid resin with light
• Melt layers of metal powder using a laser

Each layer is added and fused to the previous one until the part is complete.

4. Post-Processing and Finishing

Most 3D prints require some level of post-processing, such as:

• Removing support structures
• Cleaning excess powder or resin
• Surface finishing
• Heat treating or smoothing (process-dependent)

Engineers typically focus on dimensional accuracy and functional performance, while designers often refine visual appearance and surface quality.

What is 3D Printing Used for?

3D printing is used across multiple industries for a range of applications, including:

• Rapid prototyping for functional testing or design iteration
• Presentation-ready models for client approvals
• Functional components that are difficult or costly to make through traditional methods
• Jigs, fixtures, and tooling for manufacturing environments
• Custom or one-off parts for early-stage hardware
• Low-volume production where tooling would be prohibitively expensive

The ability to move from CAD to a physical part in days rather than weeks is one of the biggest advantages of 3D printing.

How 3D Printing Compares to Traditional Manufacturing

3D printing is well suited to early-stage development because it avoids tooling and enables fast iteration. A model can be adjusted and a new part produced within days, whereas traditional manufacturing often requires costly and time-consuming setup.

Additive processes also handle complex geometries with ease and generate far less waste, since material is added only where it’s needed. Traditional methods remain more efficient at high volumes, but for prototypes and low-volume production, 3D printing offers a greater speed, flexibility, and design freedom.

Factors That Influence 3D Print Quality

Several factors influence the quality and performance of a 3D printed part, including material choice, layer thickness, and the complexity of the geometry.

Powder-bed processes such as SLS and MJF generally provide strong, functional parts with good dimensional stability, while resin-based technologies like SLA deliver smooth, presentation-ready surfaces suited to design models.

Considering these elements early helps reduce rework, ensures a more predictable outcome, and supports smoother development cycles.

Common 3D Printing Technologies and How They Work

3D printing is not a single process but a family of technologies. Below is an overview of the 3D printing technologies we use at Truform.

FDM / FFF (Fused Deposition Modelling / Fused Filament Fabrication)

How it works: A heated nozzle extrudes a thin bead of melted thermoplastic filament, depositing it layer by layer.

Materials: PLA, ABS, PETG, Nylon, TPU, Polycarbonate, PEI (Ultem), PEEK.

Best for:

• Early prototypes
• Larger parts
• Low-cost iterations
• Flexible materials (TPU/TPE)

Why engineers and designers use FDM / FFF: It’s accessible, versatile, and cost-effective for fast design cycles.

SLS (Selective Laser Sintering)

How it works: A laser fuses powdered polymer (typically Nylon) inside a heated chamber. The unused powder supports the part, eliminating the need for external supports.

Materials: Nylon PA11, PA12, composite-filled powders.

Best for:

• Functional prototypes
• Durable components
• Complex geometries
• Small batch production

Why it matters: SLS parts are strong, accurate, and suited for demanding applications.

MJF (Multi Jet Fusion)

How it works: An array of inkjet heads applies fusing and detailing agents to a powder bed, which is then heated to bind the material.

Materials: Nylon PA11, PA12, flexible TPU.

Best for:

• Fast production
• Fine detail and accuracy
• Repeatable batches
• End-use parts

Key advantage: MJF provides excellent consistency across parts and is ideal for engineers who need predictable results.

SLA / DLP (Stereolithography / Digital Light Processing)

How it works: UV light cures liquid resin layer by layer.

Materials: Standard, tough, clear, dental, heat-resistant, and castable resins.

Best for:

• High-detail visual models
• Smooth surface finishes
• Appearance prototypes
• Intricate geometries

Why designers choose it: SLA / DLP produces polished, presentation-ready parts with minimal finishing.

3D Printing Helps Projects Run Smoothly

3D printing is a versatile, modern manufacturing approach that builds objects layer by layer from a digital design. Whether you are creating functional prototypes, detailed appearance models, or exploring low-volume production, understanding how 3D printing works helps you make confident, informed decisions.

As additive manufacturing continues to evolve, this foundational knowledge remains essential for anyone involved in product development or technical design. A clear grasp of the fundamentals also makes it easier to choose the right process for your next prototype or low-volume run.

If you’re exploring options for an upcoming project and want practical guidance on materials, processes, or feasibility, Truform is always happy to help. Get in touch to discuss the best approach for your design.