Types of 3D Printing: A Simple Guide

If you are new to the world of 3D printing, the sheer number of options can feel overwhelming. You might see acronyms like FDM, SLA, SLS, or DED and wonder what they all mean.

Basically, 3D printing is the process of creating physical objects from digital files. However, not all printers work the same way. Some melt plastic filament, some use lasers to harden resin, and others use binding agents to glue powder together.

To help you understand the landscape, we have created this complete guide covering the 8 major technologies used today. This will help you decide which method fits your project, whether you are making a simple toy, a detailed jewelry piece, or an aerospace part.

1. FDM (Fused Deposition Modeling)

FDM is the most widely used 3D printing technology in the world. If you have a printer at home, it is likely an FDM printer.

How it Works

Think of it like a computer-controlled hot glue gun. The printer feeds a spool of thermoplastic filament through a heated nozzle. The 3D printer nozzle size determines how fine or fast you can print. The nozzle moves around and deposits the melted plastic layer by layer. Once the plastic cools down, it solidifies into the final shape.

Why Use It

It is the most affordable entry point into 3D printing. Also, you have a massive choice of materials. You can easily find the best 3D printer filament for your project, or compare specific types like PETG vs PLA filament.

Pros

• Very low cost for machines and materials.
• Easy to use and safe for home environments.
• Strong parts suitable for basic mechanical use.

Cons

• Visible layer lines on the surface. However, you can learn how to smooth PLA 3D prints to make them look professional.
• Not great for extremely tiny details.

2. SLA (Stereolithography)

SLA is the grandfather of 3D printing. It is famous for producing parts with incredible smooth finishes and high precision. Unlike FDM, it uses liquid resin. If you are stuck choosing between the two, it helps to look at the key differences between resin and filament printers.

How it Works

SLA printers use a tank filled with liquid resin. A precise UV laser beam traces the shape of the layer onto the surface of the liquid. Wherever the laser hits, the liquid turns into solid plastic. This process repeats until the object is pulled out of the tank.

Why Use It

If you need to print a miniature figure with a detailed face or a casting pattern for jewelry, SLA is the standard choice.

Pros

• Extremely high resolution and detail.
• Smooth surface finish that looks professional.
• Ideal for intricate geometries.

Cons

• Liquid resin is messy and toxic. Because of the fumes, you need ventilation to keep your workspace safe.
• Prints are often brittle and fragile.

3. DLP (Digital Light Processing)

DLP is very similar to SLA. They both use liquid resin and UV light. However, there is a key difference in how they project the light.

How it Works

While SLA uses a laser pointer to draw each layer, DLP uses a digital projector screen (like a movie theater projector) to flash the entire image of a layer at once.

Why Use It

Because it projects the whole layer instantly, DLP is generally faster than SLA. This makes it popular in dentistry and mass production of small parts.

Pros

• Faster print speeds than SLA for full layers.
• High detail similar to SLA.
• Slightly more reliable due to fewer moving parts.

Cons

• Can have a pixelated surface finish on curved edges.
• Resin handling is still messy.

4. SLS (Selective Laser Sintering)

SLS is a favorite in the industrial world. It creates strong, functional parts that are ready for real-world use.

How it Works

This printer uses a bed of fine powder, usually nylon. A high-power laser draws the design on the powder, fusing the particles together. Then, a roller spreads a new layer of powder on top, and the laser sinters the next layer.

Why Use It

The biggest advantage is that you do not need support structures. The unsintered powder surrounds and supports the part during printing. This allows you to print crazy complex shapes that other printers cannot make.

Pros

• No support structures needed.
• Excellent mechanical strength and heat resistance.
• Great for functional engineering prototypes.

Cons

• Machines are expensive and large.
• The powder is messy to clean up.
• Surface finish is grainy and porous.

5. SLM / DMLS (Metal 3D Printing)

If you need real metal parts, this is the technology to use. SLM (Selective Laser Melting) and DMLS (Direct Metal Laser Sintering) are the heavy hitters of the industry.

How it Works

Similar to SLS, these machines use a bed of powder. However, instead of nylon, they use metal powders like titanium, aluminum, or steel. A powerful laser fully melts the metal powder to create a solid metal part.

Why Use It

This is used for high-end applications like rocket engine parts, medical implants, and custom automotive tools.

Pros

• Creates solid, dense metal parts.
• Extremely strong and durable.
• Reduces waste compared to traditional subtractive methods like CNC machining, which cuts away material rather than adding it.
  

Cons

• Extremely expensive machines and materials.
• Dangerous to operate (requires strict safety protocols).
• Requires extensive post-processing.

6. Binder Jetting

Binder Jetting is unique because it does not use heat during the printing process.

How it Works

A roller spreads a thin layer of powder (which can be sandstone, metal, or ceramic). Then, a print head moves over the bed and deposits a liquid binding agent (glue) onto the powder. This glues the powder together to form the shape.

Why Use It

It is one of the few technologies that can print in full color by using colored binders on sandstone powder. It is also used to make large metal parts cheaper than SLM.

Pros

• Can print in full color (Sandstone).
• Faster and cheaper than laser-based systems.
• No need for support structures.

Cons

• Parts are very fragile coming out of the printer.
• Metal parts need a secondary heating process to be strong.

7. PolyJet

PolyJet is known for its ability to print in multiple colors and materials at the same time.

How it Works

This works a lot like a standard 2D inkjet printer in your office. However, instead of ink drops on paper, it jets tiny droplets of liquid photopolymer onto a build tray. UV lights immediately cure these droplets into solid plastic.

Why Use It

It is the best choice for "looks-like" prototypes. You can print a single object that is rigid in one area and rubbery in another, all in full color.

Pros

• Multi-material and full-color capability.
• Incredible realism and surface smoothness.
• Fast printing speed.

Cons

• Very high machine and material cost.
• Parts are not very strong mechanically.
• Materials degrade over time in sunlight.

8. DED (Directed Energy Deposition)

DED is mostly used in heavy industry. You can think of it as a super-powered automated welding process.

How it Works

A nozzle feeds metal wire or powder directly into a focused laser or electron beam. The beam melts the material instantly as it leaves the nozzle, fusing it onto the existing surface.

Why Use It

You typically won't use this to print new parts from scratch. Instead, industry pros use DED to repair high-value metal parts, like fixing a broken blade on a turbine engine. It is also used to add metal features to existing objects.

Pros

• Can repair existing broken parts.
• Very fast metal deposition rates.
• Can print on huge parts.

Cons

• Low resolution and poor surface finish.
• Requires extensive machining afterwards.
• Only for industrial use.

3D Printing Considerations

Now that you know the professional landscape, how do you choose? Here are the key factors to consider.

1. Function vs. Appearance

If you need a part to hold weight or withstand heat, go with FDM, SLS, or SLM. If you just need it to look beautiful and smooth, SLA, DLP, or PolyJet are better choices.

2. Budget

FDM is the only truly budget-friendly option for home users. SLA and DLP have become affordable recently, but the resin is costly. Technologies like SLS, SLM, and PolyJet are strictly industrial machines that cost thousands of dollars. If you are strictly watching your wallet, you should look into how much a 3D printer costs upfront.

3. Environment

FDM is clean enough for an office desk. However, resin printers (SLA/DLP) need ventilation. Powder-based printers (SLS/SLM/Binder Jetting) require industrial workshop settings due to dust and safety hazards.

Final Thoughts

The world of 3D printing is vast. From the humble FDM printer on a hobbyist's desk to the massive DED machines repairing turbines, there is a technology for every application.

For most beginners, FDM remains the best starting point due to its simplicity. If you crave higher detail, SLA or DLP is the next step. However, understanding the advanced types like SLS and Binder Jetting helps you see the full potential of the industry. Once you have the right machine, you can start exploring something to 3D print to truly test your machine's capabilities.

FAQ

Which type of 3D printing is best?

There is no single "best" type. It really depends on what you need. For beginners and those on a budget, FDM is usually the best choice. However, if you need super high detail for things like jewelry, SLA is the winner. So, the best printer is simply the one that fits your specific project.

What is the strongest form of 3D printing?

SLM (Metal 3D Printing) creates the strongest parts because they are made of solid metal like titanium or steel. Among the plastic technologies, SLS is typically the strongest. It fuses nylon powder into solid parts that are tough and durable in all directions.