When it comes to 3D printing, two technologies stand out for accessibility and versatility: SLA (Stereolithography) and FDM (Fused Deposition Modeling). SLA uses light to cure liquid resin into precise parts, while FDM melts plastic filaments to build layers. Both work for prototypes, small-batch production, and even end-use parts—but their strengths, costs, and best uses vary drastically. This guide breaks down their key differences, material options, real-world applications, and how to pick the right one for your needs.
First: What Are SLA and FDM? (Core Principles)
Before comparing them, let’s clarify how each technology works—their basic processes explain why they excel at different tasks.
SLA (Stereolithography): Light-Cured Resin
SLA is one of the oldest 3D printing technologies, relying on photopolymerization (light reacting with resin to harden it). Here’s a simple breakdown:
- A vat holds liquid thermoset resin (sensitive to UV light).
- A UV laser (or LED array) traces the first layer of your part’s design onto the resin surface—curing it into a solid.
- The build platform lifts slightly, and a recoater spreads a thin layer of fresh resin over the cured layer.
- The laser repeats the process, layer by layer, until the part is complete.
- The part is removed from the vat, rinsed to remove excess resin, and cured again (post-curing) for extra strength.
Key Trait: Uses liquid resin, so it creates smooth, detailed parts with no visible layer lines.
FDM (Fused Deposition Modeling): Melted Filament
FDM is the most common 3D printing technology, especially for hobbyists and small businesses. It’s an extrusion-based process:
- A spool of thermoplastic filament (e.g., PLA, ABS) feeds into a heated nozzle.
- The nozzle melts the filament (at 180–260°C, depending on the material).
- The nozzle moves along a path defined by your 3D model, depositing the melted plastic onto the build plate.
- The plastic cools and hardens instantly, bonding to the layer below.
- The build plate lowers slightly, and the process repeats until the part is done.
Key Trait: Uses solid filament, so it’s simpler to set up and more forgiving of minor design flaws.
SLA vs. FDM: Key Comparison (Data & Details)
The table below compares SLA and FDM across 8 critical factors—cost, precision, material options, and more—using real-world data from manufacturers like Xometry and Prusa.
| Factor | SLA (Resin) | FDM (Filament) |
| Cost (Desktop Printers) | \(200–\)2,000 (resin costs \(20–\)50 per liter) | \(150–\)1,500 (filament costs \(20–\)40 per kg) |
| Cost (Industrial Printers) | \(10,000–\)100,000+ | \(5,000–\)50,000+ |
| Layer Thickness | Ultra-thin (min. 0.02 mm) – great for detail | Thicker (0.05–0.3 mm) – visible layer lines |
| Tolerance (Precision) | Tight (±0.1 mm for small parts) – ideal for fits | Looser (±0.2–0.3 mm) – better for non-critical parts |
| Surface Finish | Smooth, glass-like (no layer lines) | Rough (visible layer steps) – needs sanding for smoothness |
| Material Options | Limited (thermoset resins only) – rigid, flexible, or high-temp | Wide (thermoplastics) – PLA, ABS, PETG, TPU, and more |
| Build Size (Desktop) | Smaller (max 145×145×175 mm) | Larger (max 200×200×200 mm) |
| Build Size (Industrial) | Up to 2100×800×700 mm | Up to 914×610×914 mm |
| Post-Processing | Required (rinse, cure, remove supports) – 30–60 mins per part | Minimal (remove supports, sand if needed) – 10–30 mins per part |
| Strength | Brittle (most resins) – good for display, not load-bearing | Strong (especially ABS/PC) – works for functional parts |
Material Options: What You Can Print With SLA vs. FDM
The materials you use define your part’s strength, durability, and use case. SLA and FDM have distinct material libraries—here’s what you need to know.
SLA Resins: Precision Over Variety
SLA only uses thermoset resins (they harden permanently with light, no re-melting). While the range is smaller than FDM, resins are tailored for specific needs:
| Resin Type | Key Traits | Best Uses | Example |
| Standard Resin (e.g., 8360X, 8100) | Smooth, rigid, low cost | Prototypes, display models, jewelry casts | A toy company’s prototype action figure |
| ABS-Like Resin (e.g., 8220) | Flexible, impact-resistant | Functional parts (e.g., phone cases, hinges) | A startup’s prototype camera grip |
| High-Temp Resin (e.g., Therm 1) | Withstands up to 150°C | Parts for high-heat environments (e.g., engine components) | A mechanic’s prototype sensor bracket |
| Biocompatible Resin (e.g., eusilicone) | Safe for skin/body contact | Medical devices (e.g., surgical guides, dental models) | A dentist’s custom crown prototype |
| Transparent Resin | Clear, glass-like finish | Lenses, display cases, light fixtures | A designer’s prototype lamp shade |
Note: SLA resins are limited in color—most come in gray, black, white, or transparent. Coloring requires post-processing (painting), which adds cost.
FDM Filaments: Variety Over Precision
FDM uses thermoplastics (they melt when heated, harden when cooled)—a wide range of materials for almost any project:
| Filament Type | Key Traits | Best Uses | Cost per kg (USD) |
| PLA | Low cost, easy to print, biodegradable | Hobby projects, prototypes, display parts | \(20–\)30 |
| ABS | Impact-resistant, heat-resistant (up to 100°C) | Functional parts (e.g., gears, electronics housings) | \(25–\)40 |
| PETG | Strong, flexible, water-resistant | Outdoor parts, containers, mechanical components | \(30–\)45 |
| TPU | Soft, elastic (like rubber) | Grips, gaskets, shock absorbers | \(40–\)60 |
| Nylon PA12 | High strength, wear-resistant | Load-bearing parts (e.g., drone frames, fasteners) | \(50–\)80 |
| PC (Polycarbonate) | Ultra-strong, heat-resistant (up to 130°C) | Safety gear, high-impact parts | \(60–\)90 |
Pro Tip: FDM filaments come in dozens of colors—you can print colored parts directly, no painting needed. For example, a brand can print custom-branded phone cases in their signature color without extra steps.
Real-World Use Cases: When to Choose SLA vs. FDM
Numbers tell part of the story—but real projects show how these technologies perform in practice. Here are 3 examples where the choice between SLA and FDM made a big difference.
Case 1: Dental Crown Prototypes (SLA Wins)
A dental lab needed 20 custom crown prototypes (to test fit before making final ceramic crowns).
- FDM Option: PLA filaments are cheap, but FDM’s ±0.2 mm tolerance wasn’t tight enough—crowns didn’t fit patients’ teeth. Post-processing (sanding) took 30 mins per part, and the rough surface didn’t mimic real ceramic.
- SLA Option: Biocompatible resin (eusilicone) had ±0.1 mm tolerance—perfect fit. The smooth surface looked like real ceramic, and post-processing (rinse + cure) took 15 mins per part.
Result: The lab chose SLA—prototypes fit 100% of patients, and the dentist could approve designs faster. Cost per prototype was \(8 (vs. \)5 for FDM), but the time saved was worth it.
Case 2: Drone Frame Prototypes (FDM Wins)
A startup needed 50 durable drone frame prototypes (to test flight performance).
- SLA Option: ABS-like resin was smooth, but the frames were brittle—20% broke during crash tests. Resin cost \(40 per liter, and each frame used 50ml (\)2 per frame).
- FDM Option: Nylon PA12 filament was strong and flexible—only 5% of frames broke. Filament cost \(60 per kg, and each frame used 20g (\)1.20 per frame).
Result: The startup chose FDM—saved \(40 total (\)0.80 per frame) and got more durable prototypes. The visible layer lines didn’t affect flight performance, so sanding wasn’t needed.
Case 3: Custom Phone Cases (Depends on Needs)
A small brand wanted 100 custom phone cases (branded with their logo).
- SLA: Transparent resin made the logo pop, and the smooth surface felt premium. But resin cost \(5 per case, and painting the logo added \)1 per case (total $6).
- FDM: PETG filament in the brand’s signature blue was cheaper (\(3 per case), and the logo was printed directly (no painting). The surface was slightly rough, but adding a clear coat (\)0.50 per case) fixed it (total $3.50).
Result: The brand chose FDM for cost savings—customers didn’t mind the minor roughness, and the cases sold out faster than expected.
How to Choose Between SLA and FDM (Step-by-Step)
Follow these 4 steps to pick the right technology—no guesswork needed.
Step 1: Define Your Part’s Purpose
Ask: What will the part do?
- Display/prototype with fine details (e.g., jewelry, dental models): Choose SLA.
- Functional/load-bearing part (e.g., gears, drone frames): Choose FDM.
- Transparent/glass-like part (e.g., lenses): Choose SLA.
- Colored part (no painting) (e.g., branded cases): Choose FDM.
Step 2: Check Tolerance and Surface Needs
- Need tight tolerance (±0.1 mm) or smooth finish? SLA.
- Tolerance isn’t critical (±0.2 mm) or rough finish is okay? FDM.
Step 3: Calculate Cost (Material + Post-Processing)
- Small batches (1–10 parts): FDM is cheaper (filament costs less than resin, no post-curing).
- Parts needing precision: SLA may cost more upfront but saves time on reworks.
Example: 10 lens prototypes cost \(50 with SLA (resin + post-curing) vs. \)30 with FDM—but FDM lenses were too rough to use, so SLA was the better value.
Step 4: Consider Build Size
- Small parts (under 150mm): SLA or FDM works.
- Larger parts (over 200mm): FDM (desktop FDM printers have bigger build plates).
Yigu Technology’s Perspective on SLA vs. FDM
At Yigu Technology, we match SLA and FDM to our clients’ goals, not just their budgets. For precise parts like medical prototypes or jewelry casts, SLA’s resin-based detail can’t be beaten. For functional parts—drone frames, tool handles, or outdoor components—FDM’s filament strength and cost savings make sense. We also help with post-processing: sanding FDM parts for smoothness or post-curing SLA parts for extra durability. Our team provides side-by-side quotes and sample parts, so clients see the difference firsthand. For us, the best technology is the one that makes your part work, last, and fit your timeline.
FAQ About SLA vs. FDM 3D Printing
1. Is SLA resin toxic?
Most SLA resins are low-toxic (labeled “skin-safe”), but you should wear gloves when handling liquid resin—direct contact can cause irritation. Post-cured resin is safe (the light reaction neutralizes the chemicals). Avoid using SLA resin for food-contact parts (even biocompatible resins aren’t food-grade).
2. Can FDM print parts as strong as SLA?
Yes—FDM’s thermoplastics (like ABS or PC) are stronger and more flexible than most SLA resins. SLA parts are great for detail but often brittle; FDM parts work better for load-bearing or impact-resistant uses (e.g., drone frames, gears).
3. Which is better for beginners: SLA or FDM?
FDM is better for beginners. It’s simpler to set up (no resin handling), more forgiving of design mistakes, and cheaper to fix (filament is less costly than resin). SLA requires more care (rinsing resin, post-curing) and has a steeper learning curve for perfect parts.