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Selective Laser Sintering (SLS) is one of the most powerful 3D printing methods available. It creates strong, detailed parts without the need for support structures — making it perfect for functional prototypes and production-ready components.
But just like any process, bad design = bad results.
If your part isn’t optimized for SLS, you could face issues like:
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Warping
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Fragile or broken sections
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Build failures that waste time and money
In this guide, we’ll show you how to design for SLS success — and avoid the most common (and expensive) mistakes.
1. Understand the Basics of SLS Printing
Before we dive into tips, let’s cover how SLS works:
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A laser sinters (melts) fine nylon powder layer by layer.
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Unused powder supports the part during printing — so no support structures are needed.
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The part is removed from the powder bed, cleaned, and finished.
This process gives you great freedom in shape and design — but it comes with a few rules to follow.
2. Use Proper Wall Thickness
Minimum Wall Thickness for SLS: ~0.8 mm (0.03 in)
Anything thinner may snap, warp, or fail during post-processing.
Recommended:
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1.5–2.5 mm for strong structural parts
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Thicker walls for load-bearing or long unsupported spans
💡 Thin walls can cool unevenly, causing stress and breakage.
3. Avoid Sharp Corners and Stress Points
SLS parts can crack if stress builds up in one area — especially corners.
Use These Tips:
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Add fillets or radii to sharp internal corners
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Avoid sudden thickness changes (they cause uneven cooling)
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Don’t place holes too close to edges
4. Reduce Warping with Smart Design
Warping is caused by uneven cooling during and after the print.
Ways to Prevent Warping:
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Use ribs or gussets to add stiffness without bulk
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Hollow out large blocks (use 2–3 mm thick shells with lattice inside)
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Keep cross-sections uniform throughout the part
📌 Thicker sections cool slower, pulling and distorting your part.
5. Watch Overhangs and Narrow Features
While SLS doesn’t need supports, long overhangs and thin spikes can still sag or break.
Do:
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Use chamfers or self-supporting angles on overhangs
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Keep long features attached at both ends where possible
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Reinforce thin pins, tabs, or posts if they stick out more than 10 mm
6. Hollow Your Parts with Drain Holes
To reduce cost and improve print success:
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Hollow thick parts to use less powder and avoid overheating
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Add escape holes (3–5 mm wide) so unused powder can be removed after printing
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Parts without drain holes may trap powder or print incorrectly.
7. Use Text and Details the Right Way
SLS is great for custom engravings or serial numbers, but keep these rules in mind:
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Text Depth (engraved): at least 0.5 mm deep
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Text Height (embossed): at least 0.5 mm tall
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Use bold sans-serif fonts for best clarity
8. Mind the Orientation
Your part's orientation in the powder bed affects:
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Surface quality
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Strength along different axes
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Build success rate
Let your printing partner (like us!) choose the best orientation or talk with us during the quoting process.
9. Use Material-Specific Design Guidelines
SLS usually prints with Nylon PA12, which is strong, flexible, and slightly porous.
If you're designing for:
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Tough, functional prototypes → Use thicker walls and stiffening ribs
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Snap fits or living hinges → Use thin, flexible areas (but test first)
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Cosmetic parts → Consider dyeing or bead blasting for finish
🔍 Always check your printing partner’s material datasheet for updated tolerances and specs.
Final Tips Checklist
✅ Use minimum wall thickness of 0.8 mm (1.5 mm+ recommended)
✅ Add fillets to internal corners
✅ Hollow large parts and add escape holes
✅ Avoid long unsupported overhangs
✅ Use bold, deep text for engravings
✅ Let experts help with orientation and final checks
Conclusion
SLS is a powerful process — but great results start with great design. By following these simple rules, you’ll reduce the risk of failed prints, save money, and get parts that look and perform exactly how you want.
Ready to design your next part for SLS?
👉 Explore our Nylon PA12 and Material Options
Sources
[1] 3D Hubs. Design Guidelines for SLS
[2] HP. Design for Additive Manufacturing – MJF Best Practices
[3] Formlabs. Design Tips for Powder Bed Fusion
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