FDM vs SLA vs SLS: Which 3D Printing Technology Do You Need?

Updated March 2026 · 8 min read

FDM if you need durable parts cheap and don't care about surface finish. SLA if you need detail and smooth surfaces. SLS if you need functional parts without supports or you're making batches.

That's the short version. The rest of this guide explains when each technology makes sense, what they cost, and which compromises you're making.

FDM: Fused Deposition Modeling

A heated nozzle extrudes melted plastic filament layer by layer. Think of a hot glue gun following a precise path. It's the most common technology because it's cheap, reliable, and the materials are easy to work with.

When FDM Works Best

• Functional prototypes: Parts that need to hold screws, snap together, or take light mechanical stress
• Large parts: Build volumes up to 12x12x12 inches are common, some go bigger
• Low-cost production: Material costs $20-30 per kilogram, makes it viable for small batch runs
• Durable end-use parts: PETG and nylon FDM prints are legitimately strong

When FDM Fails

• High detail: Layer lines are visible. A 0.2mm layer height is standard, 0.1mm is possible but slow. Fine text or intricate surface detail won't look sharp.
• Smooth surfaces: You'll see layer lines. Sanding helps but takes time.
• Overhangs: Anything over 45° needs support material, which leaves marks where it contacts the part.
• Small delicate features: Thin walls (under 1mm) can be fragile, fine details can break off during support removal.

FDM Materials That Matter

PLA: Easiest to print, stiff, brittle. Good for non-functional parts. Warps in heat (don't leave it in a hot car).

PETG: Tougher than PLA, slight flex, good chemical resistance. This is what I use for most functional parts.

ABS: Strong, heat-resistant, but warps easily and needs ventilation (fumes are unpleasant). Mostly replaced by PETG in non-industrial settings.

Nylon: Very strong, flexible, abrasion-resistant. Harder to print (absorbs moisture, requires high temps). Worth it for parts that take abuse.

TPU: Flexible rubber-like material. For gaskets, phone cases, anything that needs to bend.

Carbon fiber filled: Nylon or PETG with chopped carbon fiber. Stiffer and stronger than base material, looks cool. Abrasive—wears out nozzles fast.

FDM Cost Reality

Machine cost: $300-5,000 Material cost: $20-60/kg Print speed: 40-200 mm³/s (consumer machines) Service pricing: $0.08-0.15 per gram + setup fee

A fist-sized part costs $30-80 to have printed at a local shop.

SLA: Stereolithography (Resin Printing)

A UV light source cures liquid resin layer by layer. Each layer is an entire cross-section of the part, printed at once. The build platform lifts slightly, liquid resin flows in, next layer cures.

When SLA Works Best

• High detail: 0.05mm layer heights are standard, 0.025mm possible. You can print legible 6-point text.
• Smooth surfaces: Resin prints come off the machine nearly glass-smooth. Minimal post-processing needed.
• Small intricate parts: Jewelry, miniatures, dental models, anything where detail matters more than size.
• Prototypes for injection molding: The smooth surface finish shows what the final molded part will look like.

When SLA Fails

• Large parts: Most resin printers have 6x6x8 inch build volumes. Large-format resin printers exist but cost $3,000+ and use expensive resin.
• Durability: Standard resin is brittle. Drop it and it cracks. Tough resins exist but they're still not as durable as FDM materials.
• Cost: Resin costs $40-150 per liter. A solid part uses a lot of resin. Hollow parts save material but need drain holes.
• Messiness: Resin is toxic until cured. You need gloves, ventilation, and a washing/curing station. It's not a kitchen-table operation.

SLA Resin Types

Standard resin: Brittle, high detail, cheap ($40-60/L). For display pieces and non-functional prototypes.

Tough resin: Less brittle, can handle some flex. Still not as durable as PETG. Used for functional prototypes ($80-120/L).

Flexible resin: Rubber-like, shore hardness 50A-80A. For gaskets, grips, soft-touch parts ($80-120/L).

Castable resin: Burns out cleanly for lost-wax casting. Jewelry industry standard ($100-150/L).

Dental/medical resin: Biocompatible, FDA-approved for oral use. Expensive ($120-250/L) and requires specific printers.

High-temp resin: Can withstand 150-200°C. For injection mold tooling or under-hood automotive parts ($100-180/L).

SLA Cost Reality

Machine cost: $300-6,000 Material cost: $40-150/L Print speed: 30-80mm height/hour Service pricing: $0.20-0.50 per gram + setup fee

A detailed miniature (30g) costs $15-30 to have printed.

SLS: Selective Laser Sintering

A laser fuses nylon powder layer by layer. The powder bed supports the part, so no support structures needed. Unfused powder is reused for the next print.

When SLS Works Best

• Functional parts: SLS nylon is strong, flexible, and durable. Parts can replace injection-molded components.
• Complex geometry: No supports means you can print impossible overhangs, interlocking assemblies, and fully-enclosed moving parts.
• Batch production: You can pack the powder bed with dozens of parts, all printing simultaneously. Cost per part drops dramatically.
• Engineering prototypes: When you need parts that accurately represent final production material properties.

When SLS Fails

• Cost: Machines start at $10,000. Material is $80-150/kg. Service pricing is $1-3 per gram. This is not hobby-level technology.
• Surface finish: SLS parts have a grainy texture from the powder. Sanding helps, but you won't get SLA-smooth without significant post-processing.
• Size limits: Most SLS machines have 10-15 inch build volumes. Bigger machines exist but cost $100k+.
• Material selection: Mostly nylon (PA11 and PA12). Some machines can print TPU or specialty powders, but choices are limited compared to FDM.

SLS Materials

PA12 (nylon 12): Standard SLS material. Strong, slightly flexible, good chemical resistance. This is what most shops use.

PA11 (nylon 11): Bio-based, slightly more flexible than PA12, better impact resistance.

Glass-filled PA: Stiffer and stronger than unfilled nylon. For structural parts and high-stress applications.

Flame-retardant PA: Meets UL94 standards. For electronics housings and applications where fire safety matters.

TPU (flexible): Rubber-like SLS parts. Less common because TPU powder is finicky and expensive.

SLS Cost Reality

Machine cost: $10,000-250,000 Material cost: $80-150/kg Print speed: 20-50mm height/hour Service pricing: $1.00-3.00 per gram + setup fee

A fist-sized functional part costs $150-400 to have printed.

Head-to-Head Comparison

| Criteria | FDM | SLA | SLS | |--------------|---------|---------|---------| | Detail | Poor (0.1-0.3mm) | Excellent (0.025-0.05mm) | Good (0.1mm) | | Surface finish | Rough | Smooth | Grainy | | Strength | Good | Poor | Excellent | | Size | Large (12"+ common) | Small (6-10") | Medium (10-15") | | Cost | Low | Medium | High | | Speed | Fast | Medium | Slow | | Support removal | Required, leaves marks | Required, minimal marks | None needed | | Material variety | Huge | Medium | Limited | | Post-processing | Sanding, painting | Minimal | Sanding, dyeing |

Decision Matrix: Which Technology to Use

You Need FDM If:

• Budget is under $100 per part
• Part is larger than 6 inches in any dimension
• You need durable functional parts
• Surface finish doesn't matter (or you'll sand/paint anyway)
• You're prototyping mechanical assemblies
• Example use cases: Brackets, enclosures, jigs, fixtures, cosplay armor, automotive parts

You Need SLA If:

• Detail and surface finish are critical
• Part is small (under 6 inches)
• It's a display piece or presentation model
• You're making jewelry masters or dental models
• You need to cast the part (lost-wax casting)
• Example use cases: Miniatures, jewelry, architectural details, dental aligners, injection mold prototypes

You Need SLS If:

• You need production-quality functional parts
• Complex geometry with impossible overhangs
• Batch production (10-100+ identical parts)
• No support marks are acceptable
• Budget is $150+ per part
• Example use cases: End-use manufacturing, aerospace components, medical devices, performance automotive parts

Hybrid Approaches

You don't have to pick one technology for an entire project.

Prototype on FDM, produce on SLS: Iterate fast with cheap FDM prints, then get final functional parts in SLS when design is locked.

Detail parts in SLA, structure in FDM: Print a helmet in FDM ($60), add fine surface details in SLA ($20). Assemble and paint as one piece.

Batch small parts in SLS, large parts in FDM: A product might have 20 small SLS clips ($2 each) and one large FDM housing ($80). Use the right technology for each component.

What Most People Should Do

If you're not sure, start with FDM. It's cheap, fast, and handles 80% of use cases. You can always upgrade to SLA or SLS later if you hit FDM's limitations.

If you need detail or smooth finish, use SLA. The cost difference isn't massive for small parts, and the quality difference is dramatic.

If you need functional parts at scale, budget for SLS. It's expensive but worth it when you're past prototyping and need parts that work reliably.

Material Properties Compared

| Property | PLA (FDM) | PETG (FDM) | Nylon (FDM) | Standard Resin (SLA) | Tough Resin (SLA) | PA12 (SLS) | |--------------|---------------|----------------|-----------------|-------------------------|-----------------------|----------------| | Tensile strength | 50 MPa | 53 MPa | 75 MPa | 38 MPa | 55 MPa | 48 MPa | | Elongation at break | 6% | 50% | 300% | 12% | 30% | 20% | | Heat deflection | 50°C | 70°C | 100°C | 45°C | 60°C | 170°C | | Impact resistance | Low | Medium | High | Very low | Low | High | | Chemical resistance | Low | Medium | High | Medium | Medium | High |

(These are typical values—specific brands and formulations vary.)

The Part Size Problem

FDM dominates for large parts because:

• Build volumes up to 16x16x16 inches are affordable ($2,000 machines)
• Material costs $20-30/kg, so a 500g large part costs $10-15 in plastic

SLA struggles with large parts because:

• Most resin printers top out at 8x8x10 inches
• Resin costs $60-100/L, and solid parts use a lot of resin
• Large-format resin printers (12x12 inch+) cost $4,000-10,000

SLS is middle-ground:

• 10x10x14 inches is typical
• Powder costs $100/kg, but you reuse unfused powder
• Large parts are feasible but expensive ($200-600 range)

If your part is bigger than 8 inches, FDM is probably your only affordable option.

The Detail Problem

SLA dominates fine detail because:

• 0.025mm layers are achievable (that's 25 microns)
• Laser spot size can be 50-100 microns
• Surface is smooth out of the machine

FDM struggles with detail because:

• 0.1mm layers are common, 0.05mm possible but slow
• Nozzle diameter is 0.4mm typically (limits fine feature size)
• Layer lines are always visible

SLS is middle-ground:

• 0.1mm layers typical
• Detail is good but not SLA-level
• Surface texture hides fine details somewhat

If you need to print legible 8-point text or intricate filigree, use SLA.

The Strength Problem

SLS produces the strongest parts:

• Nylon is inherently tough
• Powder bed prevents warping, so parts have consistent properties
• No layer adhesion issues

FDM is second if you print correctly:

• Nylon and PETG are strong materials
• Layer adhesion is the weak point (parts can delaminate)
• Print orientation matters—parts are strongest perpendicular to layer lines

SLA is weakest:

• Resin is brittle
• UV exposure and moisture degrade parts over time
• Tough resins help but still don't match FDM nylon or SLS

If the part will take mechanical stress, use SLS or FDM with nylon/PETG.

Finding the Right Shop

Most 3D printing shops offer FDM. Many offer SLA. Few offer SLS.

For FDM and SLA: Search by your state and contact 2-3 shops. Ask what materials they stock and what their turnaround time is.

For SLS: Filter by technology or specialty. SLS shops often focus on engineering and production clients. Be prepared to discuss your part's function and requirements.

The Real Decision

Technology matters less than matching the requirements to the method:

• Cheap, big, functional? FDM.
• Detailed, small, smooth? SLA.
• Strong, complex, batch production? SLS.

Most projects fit one of those categories cleanly. If yours doesn't, talk to a shop that offers multiple technologies—they'll recommend the best approach based on your actual needs, not what machine they happen to own.

Need help deciding which technology fits your project? Find a shop that offers multiple printing methods and can recommend the best approach.