3D printing — also called additive manufacturing — is a family of processes that build physical parts by adding material layer by layer from a digital 3D model. Unlike traditional manufacturing, which subtracts material from a solid block (CNC machining) or forces material into a mold (injection molding), additive processes build up the part from nothing. That fundamental difference unlocks geometries, lead times, and economics that older processes cannot match.

This guide walks through how 3D printing actually works, the seven main technology families you will encounter, and how to pick the right one for your project.

How 3D printing works — the common workflow

Every 3D printing process follows the same basic pipeline:

  • Design a 3D model in CAD software (SolidWorks, Fusion 360, Onshape, Rhino, or similar).
  • Export an STL, STEP, or 3MF file that captures the geometry as a mesh or parametric surface.
  • Slice the file — specialized software splits the 3D geometry into thin horizontal layers and generates a toolpath the printer can execute.
  • Print the part — the printer builds each layer in sequence, bonding the new layer to the one below.
  • Post-process — remove supports, sand or smooth surfaces, apply finishes if needed.
That workflow is consistent across every 3D printing technology. What changes is how each process lays down each layer.

The seven main 3D printing technologies

1. FDM — Fused Deposition Modeling

The most common 3D printing technology. A thermoplastic filament is melted through a heated nozzle and deposited in layers. Materials: PLA, PETG, ABS, TPU, PC, carbon-fiber composites. Best for: functional prototypes, jigs, large parts, cost-sensitive projects.

2. SLA — Stereolithography

A UV laser cures liquid photopolymer resin one layer at a time. Produces the smoothest surfaces and highest dimensional accuracy in the catalog. Materials: standard resins, tough resins, flexible elastomers, castable patterns. Best for: visual prototypes, snap-fit validation, jewelry, dental.

3. MJF — Multi Jet Fusion

An HP-developed process that uses inkjet heads to deposit a fusing agent onto a nylon powder bed, then fuses the layer with IR lamps. Produces isotropic, production-grade nylon parts with batch consistency. Best for: production parts, bridge manufacturing, end-use nylon components.

4. SLS — Selective Laser Sintering

Similar to MJF, but uses a CO2 laser to fuse powder point by point. Nylon-based, with specialty material options including TPU and glass-filled grades. Best for: production nylon parts when specialty materials matter.

5. DMLS / SLM — Metal Powder Bed Fusion

A laser fuses metal powder layer by layer in an inert atmosphere. Produces fully dense metal parts in titanium, stainless steel, aluminum, Inconel, and more. Expensive and slow, but unmatched for complex metal geometries. Best for: aerospace, medical implants, tooling inserts.

6. Material Jetting (PolyJet, VCJ)

Inkjet heads deposit droplets of photopolymer that are cured in place by UV light. Capable of multi-material and full-color printing in a single build. Best for: full-color prototypes, anatomical models, soft-hard multi-material assemblies.

7. Binder Jetting

A binder agent is selectively deposited onto a powder bed, binding the powder into green parts that are later sintered. Used for metal, ceramic, and sand casting applications. Best for: high-volume metal production, sand casting molds, ceramic prototypes.

How to pick the right technology for your part

Technology selection usually comes down to four questions:

  • What does the part need to do? Functional test, visual prototype, end-use production, presentation model?
  • What mechanical properties does it need? Stiffness, toughness, temperature resistance, flexibility?
  • How many parts do you need? One-offs favor SLA and FDM. Production runs favor MJF and SLS. Thousands of identical parts favor injection molding (not 3D printing at all).
  • What is your budget and timeline? FDM is cheapest and fastest for most projects. SLA and MJF cost more but deliver better surfaces or mechanical properties. Metal printing is the most expensive.
A good rule of thumb: if you do not know what to choose, start with FDM for cost-sensitive functional prototypes, SLA for visual prototypes, and MJF for production runs. Upload your part to our quoter and we will recommend the right technology and material based on your application.

What 3D printing is good at — and what it is not

3D printing is a genuine production technology for certain parts and a research tool for others. It is good at:

  • Complex geometry (undercuts, internal channels, lattices)
  • Low-volume production (under ~2,000 identical parts)
  • Rapid iteration (no tooling, no mold retool fees)
  • Consolidating assemblies into single pieces
  • Parts that are still being designed
It is not the right choice for:
  • High-volume production of simple geometries (injection molding wins)
  • Parts that need ultra-tight tolerances below ±0.05mm (CNC wins)
  • Cosmetic Class A surfaces without post-processing
  • Materials not available in the 3D printing catalog (many engineering polymers)
3D printing is one tool among many. The best manufacturing partners know when to use it and when to recommend something else.

Ready to start?

If you are new to 3D printing, the fastest path to a useful part is to upload your CAD file and talk to an engineer about your application. We run FDM, SLA, Industrial SLA, MJF, and FGF under one roof in Brooklyn, NY. Same-day quotes, 2–3 day lead times on prototypes, 5–7 days on production runs.