3D Printing
Additive manufacturing — layer by layer, complexity becomes free
Topology Optimization
Topology optimization removes material from regions that carry no structural load, producing forms impossible with subtractive manufacturing. The algorithm distributes material only where stress flows, creating organic skeletal structures that are simultaneously lighter and stronger than solid equivalents.
SIMP Method
Solid Isotropic Material with Penalization. Iteratively redistributes material density. Standard algorithm in Altair OptiStruct, nTopology, and Fusion 360.
Lattice Infill
Topology optimization at the micro-scale: gyroid, Schwartz P, octet truss, and Kelvin cell infill structures replace solid material with graded lattices.
Multi-Load Cases
Real parts experience many loading conditions. Optimization over multiple simultaneous or alternating loads produces more robust structures.
FEA Validation
Finite Element Analysis validates optimized designs before print. Stress concentration, deformation, and safety factor verified computationally.
The Slicing Process
Slicer software converts 3D geometry (STL, 3MF, OBJ) into layer-by-layer toolpath instructions (G-code). Every slicing parameter — layer height, infill pattern, support strategy, perimeter count — affects structural properties, surface quality, print time, and material use.
Layer Height
0.1–0.3mm for FDM. Thinner = smoother surface, longer print. Layer height is the primary quality-speed trade-off lever in FDM printing.
Infill Patterns
Grid, gyroid, honeycomb, triangles, cubic, lightning — each pattern has different isotropy, strength-per-gram, and print speed characteristics.
Support Structures
Auto-generated supports for overhangs >45°. Tree supports (Chitubox, Bambu, Cura) minimize contact area and material use.
Perimeters / Walls
Outer perimeters determine surface quality and part strength. 2–4 perimeters typical; structural parts may use 6+ or 100% infill perimeters.
Printing Technologies
Additive manufacturing encompasses radically different physical processes. Each technology trades resolution, material range, build volume, surface quality, and cost differently. The right technology depends on the application, not just the available budget.
FDM
Fused Deposition Modeling. Thermoplastic filament extruded through heated nozzle. Most accessible: Bambu Lab, Prusa, Creality. Layer height 0.1–0.3mm.
SLA / MSLA
Stereolithography. UV-cured photopolymer resin. Sub-0.05mm detail, smooth surfaces. Formlabs, Elegoo, Anycubic. Brittle without post-cure.
SLS
Selective Laser Sintering. Nylon powder fused by laser. No support structures needed. Best for functional assemblies. Industrial: EOS, Fuse 1 (Formlabs).
DMLS / SLM
Direct Metal Laser Sintering. Metal powder fused by high-power laser. Titanium, Inconel, stainless steel. Aerospace, medical, tooling applications.
Binder Jetting
Liquid binder deposited onto powder bed. High-speed multi-material. HP Multi Jet Fusion, ExOne. Used for sand casting molds and full-color parts.
Material Jetting
Photopolymer droplets deposited and UV-cured. Stratasys PolyJet, 3D Systems ProJet. Multi-material, multi-color in one print. Dental, product design.
Material Science
Material choice determines everything: mechanical properties, thermal performance, chemical resistance, and biocompatibility. The range of printable materials has expanded from basic PLA to engineering thermoplastics, composites, ceramics, bio-inks, and multi-material gradient structures.
PLA
Polylactic acid. Biodegradable, easy to print, brittle. Ideal for prototypes, art, and non-structural parts. Biodegrades in industrial composters.
PETG
Balance of strength, flexibility, and ease of printing. Chemical resistance. Food-safe variants. Preferred for functional prototypes and enclosures.
TPU / TPE
Flexible thermoplastics. Shore hardness 60A–95A. Gaskets, grips, wearables, shock absorbers. Stretchable up to 600% elongation at break.
Carbon Fiber Composites
Chopped CF in Nylon or PLA matrix: 2–5× stiffness of base polymer. Continuous CF (Markforged): aerospace-grade strength-to-weight ratio.
Post-Processing
The print is rarely the final product. Post-processing transforms rough layer-line surfaces into finished parts: support removal, surface treatment, heat treatment, plating, painting, and functional finishing. For SLA and resin prints, UV post-cure is mandatory for full material properties.
Sanding & Priming
Wet sanding from 80–2000 grit removes layer lines. Polyurethane primer fills micro-texture. Achieves surface roughness of Ra 0.1–0.5μm.
Vapor Smoothing
Acetone vapor (ABS) or Polymaker Polysher (ASA/PLA) reflow the surface thermally. Requires ventilation. Achieves injection-molded appearance in minutes.
Electroplating
Conductive paint + electroplating deposits copper, nickel, or chrome on plastic substrates. Used for decorative metal finish and EMI shielding.
HIP (Hot Isostatic Press)
Applied to metal SLS/DMLS parts. Eliminates internal voids via isostatic pressure at elevated temperature. Required for aerospace fatigue life compliance.
Design for Additive Manufacturing
DfAM inverts the design constraints of subtractive manufacturing. Complexity is nearly free — undercuts, internal channels, overhangs, and organic geometry impose no machining cost penalty. But new constraints emerge: anisotropy, support accessibility, and layer bonding must be designed for, not against.
Internal Channels
Conformal cooling channels in injection molds match the mold surface geometry — impossible with drilled channels, trivial with DMLS. Reduces cycle time 20–40%.
Overhang Rules
FDM overhang limit: 45° from vertical without supports. SLA: 60–70°. SLS: no limit. Orient parts to minimize supports and maximize surface quality on critical faces.
Minimum Wall
FDM: 0.8mm (2× nozzle diameter). SLA: 0.4mm. DMLS: 0.3mm. Thin walls risk warping, delamination, or print failure — check with slicer preview.
Part Consolidation
Replace assemblies of 10+ machined parts with 1–2 printed parts. Reduces fasteners, alignment fixtures, and assembly labor. GE's LEAP fuel nozzle: 20 parts → 1.
Artists & Designers
These practitioners demonstrate that additive manufacturing is not merely a fabrication method but a design philosophy — one that enables forms, structures, and systems previously impossible to realize.
Neri Oxman
Mediated Matter group. Multi-material printing mimicking biological gradient structures. Silk pavilion, melanin-graded glass, and cellular architecture.
Michael Hansmeyer
Subdivided columns with millions of facets — 3D-printed in segments. Computational form-finding produces Gothic complexity from algorithmic process.
Joris Laarman
Bone Chair: topology-optimized seating grown algorithmically. MX3D bridge: robotic WAAM steel printing at architectural scale in Amsterdam.
Iris van Herpen
SLS nylon garments with interlocked chain-mail structures impossible with textile manufacturing. Pioneered wearable additive manufacturing at couture scale.
Branch Technology
Free-form cellular composite printing. Large-format FDM robot extrudes carbon fiber reinforced structures used as architectural panels and pavilions.
Pia Gruber / Grossman
High-resolution SLA for jewelry and art. Demonstrates how resin printing enables sub-millimeter filigree impossible with traditional casting or machining.
rAndom International
Rain Room, Swarm Study. Use 3D printing for custom sensor housings, fluid simulation molds, and structural components of large kinetic installations.
Nervous System
Hyphae Lamp, Kinematics dress. Algorithmic design inspired by natural growth. SLS nylon jewelry and garments with 2000+ interlocked printed hinges.
Glossary
Core vocabulary of additive manufacturing, material science, and design for AM.
- FDM
- Fused Deposition Modeling. Extrudes thermoplastic filament layer by layer. Most accessible AM process. Also called FFF (Fused Filament Fabrication).
- SLA
- Stereolithography Apparatus. UV laser or masked LCD cures liquid photopolymer resin layer by layer. Highest detail among consumer processes.
- SLS
- Selective Laser Sintering. CO₂ laser fuses powder (nylon, glass-filled, rubber). No support structures. Best functional part quality without post-process finishing.
- DMLS
- Direct Metal Laser Sintering. High-power fiber laser melts metal powder. Titanium, Inconel, steel, aluminum. Used in aerospace and medical implants.
- G-Code
- Machine instruction language for CNC and 3D printers. Specifies position (X,Y,Z), extrusion (E), temperature (M104/M109), fan speed, and movement type.
- Topology Optimization
- Computational method removing material from low-stress regions while maintaining structural performance. Produces organic, biomorphic forms.
- Infill
- Internal structure density and pattern. 0% = hollow shell; 100% = solid. Typical functional parts: 15–40%. Pattern affects anisotropy and strength direction.
- Gyroid
- Triply periodic minimal surface (TPMS). Produces isotropic infill — equal strength in all directions. Also used as scaffold in tissue engineering.
- Support Material
- Sacrificial printed structure that supports overhangs during printing. Removed mechanically or dissolved (PVA in water, HIPS in limonene).
- Warping
- Differential thermal contraction causing print corners to lift from bed. Mitigated by heated enclosures, bed adhesion (PEI, glue, ABS slurry), and brim printing.
- Layer Adhesion
- Bond strength between deposited layers. Determines Z-axis tensile strength. Typically 20–50% of XY strength in FDM. Improved by higher temperature and slower speed.
- Anisotropy
- Direction-dependent mechanical properties. FDM parts are weakest in Z (layer separation). SLS parts approach isotropy. Design must account for print orientation.
- DfAM
- Design for Additive Manufacturing. Design philosophy exploiting AM capabilities: internal channels, organic geometry, part consolidation, and gradient material.
- Post-Cure
- UV exposure after SLA/MSLA printing that completes resin polymerization. Required for full mechanical properties and reduces tackiness and brittleness.
- Part Consolidation
- Replacing multi-component assemblies with fewer printed parts. GE LEAP nozzle: 20 parts → 1. Eliminates fasteners, welds, and alignment fixtures.
- Voxel
- 3D pixel — the fundamental unit of some AM processes (Material Jetting). Enables gradient material, color, and property control at the voxel level.
- Build Volume
- Maximum printable geometry envelope (X×Y×Z). Consumer FDM: 220–350mm. Large-format industrial: 500–1000mm. Pellet extrusion: meters scale.
- Overhang Angle
- Angle from vertical that self-supporting geometry can achieve. FDM: ~45°. SLA: ~60°. Beyond limit, support structures required or print quality degrades.
- Nozzle Diameter
- Determines minimum feature size and maximum extrusion rate. 0.4mm standard; 0.25mm fine detail; 0.8–1.0mm fast structural printing.
- Generative Design
- AI/optimization-driven form-finding using performance constraints as inputs. Autodesk Fusion, nTopology. Explores thousands of valid topologies computationally.
- 3MF
- 3D Manufacturing Format. Open XML-based format replacing STL. Preserves color, materials, metadata, and lattice data. Industry standard for modern slicers.
- WAAM
- Wire Arc Additive Manufacturing. MIG/TIG welding robot deposits metal beads. Large-scale metal AM (meters). MX3D used it to print an Amsterdam canal bridge.