TWS earbuds
Ergonomic chambers, charging-case interfaces and acoustic rear volumes — revisions need no tooling, and multiple parts per build keep the batch consistent.
- Chamber + case fit
- Minimum wall thickness 0.6 mm
- Revisions are a file change
DLP Additive Manufacturing · Precision Hearables
DLP 3D Printing
for Hearables
DLP photopolymer service with 25 μm layers and 22 μm projection pixels. From ear-impression scans to finished shells, structural parts and acoustic chambers — 10–500 units formed in a single build, first articles in 48 hours.
- 10–500 unitsSmall-batch MOQ
- ±0.03 mmFeature tolerance
- 0.4 mmMinimum through-hole
- 48 hFirst delivery
22 μmProjection pixel (4K DLP engine)
25–100 μmLayer thickness
±0.03 mmFeature tolerance (≤30 mm)
405 nmLight engine wavelength
Ra 1.6 μmSurface roughness after finishing
Positioning
Design precision
should not be dictated by the process
Injection moulding needs tooling, CNC needs toolpath planning, and every structural revision restarts a cost and lead-time cycle. In hearables — small chambers, dense structures, fast iteration — the process often decides before the design does.
DLP reverses that order: chambers, sound tubes and assembly features are formed in one piece, revisions require only a new file, and 10 units follow the same precision standard as 500.
Our process optimisation is dedicated to hearables: dimensional tolerance, tube bore, snap-fit clearance and skin-contact safety each map to a defined material and post-processing route.
Application scenarios
Four hearables categories,
each with a different priority
TWS prioritises fit and batch consistency, HiFi prioritises acoustic structure and internal volume, hearing aids prioritise contact safety, and wearable devices prioritise sandwich structures and cable routing.
Custom in-ear (HiFi)
Multi-driver chambers, crossover layout and labyrinth tubes formed in one piece; clear parts make internal structure directly visible.
- Supports 2–8 driver chambers
- Tube bore 0.8–2.0 mm
- Clear parts available
Hearing aids and protection
Shell surfaces rebuilt from ear-impression data with left and right modelled separately; biocompatible options for contact parts.
- Rebuilt from impression / intraoral scans
- Independent L/R modelling
- Contact material options
Wearable audio devices
Sandwich structures, cable channels and sensor mounts formed in one piece for structural validation and small-batch trial production.
- Sandwich structures and cable channels
- Insert bores / threads
- Rapid structural validation
Manufacturing capability
Precision hearables parts,
formed in one piece
We optimise exclusively for hearables and acoustic devices: chamber dimensions, tube bore, snap-fit clearance and contact-part safety each have a matched material and post-processing route.
Custom in-ear shells (CIEM)
Shell geometry is rebuilt from ear-impression scans or intraoral scans, then fitted with balanced-armature drivers, crossover layout and tube routing. One-piece forming removes assembly error.
- Supports 2–8 driver chambers with front/rear separation
- Custom tube bore from 0.8–2.0 mm
- Biocompatible options for ear-canal contact parts
Headphone structural parts
Headbands, cup frames, sliders, hinges and decorative panels — thin-wall ribs and snap features formed in one piece, eliminating multi-part assembly.
- Minimum wall thickness 0.6 mm
- Snap-fit tolerance ±0.05 mm
- Threads, insert bores and cable channels
Acoustic chambers and sound tubes
Cavity and sound path are formed as one part, removing lot-to-lot variation from bond lines. Damper seats, pressure-relief ports and multi-tube splits are supported.
- Minimum through-hole 0.4 mm
- Chamber consistency better than assembled parts
- Clear parts for internal inspection
Silicone casting masters
High-precision masters are used to cast silicone tips, sleeves and small-batch soft parts, transferring surface detail directly to the finished component.
- Surface Ra ≤1.6 μm after finishing
- Parting lines and location features designed in
- Each master supports repeated casting
Rapid validation and small-batch production
First articles in 24–48 hours for assembly checks, fit testing and acoustic tuning; once the revision is approved, the same process scales to 10–500 units.
- Whole-plate exposure for high part-to-part consistency
- 8–40 parts per build (depending on size)
- Production starts once the first article is approved
01 / Form design
Let ear geometry become the product form
Shell models are rebuilt from impression or intraoral scans, with one-piece forming reducing assembly error. Form no longer compromises to the process — fit and appearance can both hold.
02 / Structural forming
Structure, acoustics and assembly,
formed in the same part
Chambers, sound tubes and driver mounts are formed in one piece, removing lot-to-lot variation from bond lines. Damper seats, relief ports and multi-tube splits are supported.
- Tube bore0.8–2.0 mm
- Minimum through-hole0.4 mm
- Minimum stable wall0.6 mm
- Snap-fit tolerance±0.05 mm
- Stable detail size0.15 mm
- Parts per build8–40 parts
03 / Accuracy
Accuracy is proven by repeatable numbers,
not adjectives
Both are photopolymer processes, but area-exposure DLP and laser-scanning SLA perform very differently on small-batch hearables parts. Whole-layer exposure cures every part in the build at once.
25 μmMinimum layer height
22 μmXY projection pixel
±0.03 mmFeature tolerance (≤30 mm)
0.4 mmMinimum through-hole
0.6 mmMinimum stable wall
Ra 1.6 μmSurface roughness after finishing
| Item | DLP photopolymer (in-house) | Laser SLA | FDM extrusion |
|---|---|---|---|
| Forming method | Whole-layer exposure | Laser point scanning | Molten extrusion line |
| Minimum layer height | 25 μm | 25 μm | 100 μm |
| XY detail | 22 μm pixel | 80–140 μm spot | 400 μm nozzle |
| Small-batch efficiency | High — whole plate cures together | Medium — point-by-point scanning | Low — part-by-part deposition |
| Surface quality | Fine — layer lines nearly invisible | Fine | Visible layer lines |
| Best suited to | Small hearables parts, fine features, 10–500 units | Large, high-precision single parts | Large functional prototypes |
For parts over 100 mm or cosmetic parts with extreme surface requirements, we recommend another process rather than forcing DLP.
04 / Materials
Choose material by product requirement,
not by what happens to be in stock
Hearables parts hinge on contact safety, dimensional stability and acoustic performance. The table lists measured ranges for common materials; the exact grade and certification documents are confirmed per application before ordering.
Standard ABS-like grey
Dimensionally stable, sharp detail
- Tensile strength
- 55 MPa
- Elongation at break
- 6%
- Heat deflection
- 62 ℃
- Typical applications
- Structural parts, appearance checks
Tough resin
Impact resistant, snap features flex
- Tensile strength
- 48 MPa
- Elongation at break
- 25%
- Heat deflection
- 58 ℃
- Typical applications
- Snap fits, hinges, thin-wall parts
Biocompatible translucent
For skin / ear-canal contact
- Tensile strength
- 50 MPa
- Elongation at break
- 12%
- Heat deflection
- 60 ℃
- Typical applications
- Shells, tips, contact parts
High-temperature resin
High rigidity, low creep
- Tensile strength
- 62 MPa
- Elongation at break
- 3%
- Heat deflection
- 180 ℃
- Typical applications
- Acoustic chambers, test fixtures
Clear resin
Transparent after polishing, internals visible
- Tensile strength
- 52 MPa
- Elongation at break
- 8%
- Heat deflection
- 55 ℃
- Typical applications
- Clear shells, light guides
Casting resin
Low ash, investment castable
- Tensile strength
- 45 MPa
- Elongation at break
- 5%
- Heat deflection
- 60 ℃
- Typical applications
- Metal casting masters, jewellery prototypes
Values are typical for common grades and vary with batch and post-processing. For ear-canal contact parts, describe the use case and we will specify a grade with the corresponding biocompatibility documentation.
05 / Surface finishing
From sanding to painting: four finishing tiers
The finishing tier follows the part's final use. Further right means a surface closer to a finished cosmetic part, with a corresponding increase in lead time.
- 01
Draft stage
Can be sanded / polished
- 02
Rough stage
Can be hand painted
- 03
Fine stage
Can proceed to automated painting
- 04
Polished stage
Ready for assembly
Photopolymer parts still show fine layer lines on curved surfaces. The standard route is sanding plus blasting for a uniform matte finish; clear parts add step sanding and polishing. Polishing is manual work and is itemised in the quote.
Process photos
Every step, from plate layout to finished part
Whole-layer exposure cures every part in the build at once. Below are plate layout, forming, chamber and modelling examples.
Process
From file to finished part,
eight controlled process steps
Each step has a defined parameter range and delivery checkpoint, and batch orders ship with lot, material and inspection records.
-
01
File check and repair
Printability is checked first: wall thickness, normals, non-manifold edges, minimum features and assembly clearance. Issues are listed with recommendations.
STL / STEP / 3MF / OBJWall thickness ≥0.6 mm0.5–4 h -
02
Orientation and supports
Orientation follows load direction, critical dimensions and cosmetic faces; support contacts avoid mating and visible faces.
Support contact ≤0.3 mmCritical faces up0.5–1 h -
03
Slicing and exposure strategy
Layer height and anti-aliasing follow feature size, with exposure allocated per cross-section to compensate shrinkage.
25 / 50 / 75 / 100 μmXY 22 μm0.5 h -
04
DLP layer-by-layer exposure
A 405 nm engine projects the full cross-section onto the vat floor, curing every part in the build at once.
Whole-plate exposure405 nm light engineBy part height -
05
Solvent cleaning
Two-stage cleaning: soak to dissolve residual resin, then brief ultrasonics for fine holes and tube bores.
Two-stage IPA cleaningBores blown clean0.3–0.5 h -
06
Second-stage curing
Measured post-cure at the wavelength matched to the resin, balancing surface dryness against mechanical properties.
Parameters by gradeConsistency records0.5–1 h -
07
Support removal and finishing
Supports are cut and sanded through successive grits, with mating faces finished to assembly feel; clear parts add polishing.
400–2000 gritBlasting / polishing0.5–2 h -
08
Dimensional and visual inspection
Critical dimensions are sampled or fully inspected against the drawing; appearance is compared with the approved sample.
Caliper / vision system100% inspection of critical dimensionsRecorded per part
Process scenarios
Four stages,
decide whether a shell reaches production
From equipment and plate layout to chamber structure, surface finishing and custom modelling, each stage has its own process choices. Shipped-product case studies are on the case studies page.
Equipment and plate layout
Whole-layer exposure cures every part in the build together; small batches need no tooling.
- 25–100 μmLayer height
- 8–40 partsParts per build
- 48 hFirst-article lead time
Chambers and acoustic paths
Driver mounts and sound tubes are integrated into one shell, so assembly needs only a single bonding step.
- 0.4 mmMinimum through-hole
- 0.6 mmMinimum wall
- ±0.03 mmDimensional tolerance
Surface finishing and coating
Sanding, blasting, polishing or coating are selected by application; clear parts can add polishing for transparency.
- Ra ≤1.6 μmAfter finishing
- 4 optionsPost-processing
- PolishableClear parts
Ear-impression modelling
Shell surfaces are rebuilt from impression or intraoral scan data, modelled separately for left and right and delivered as a pair.
- 2 piecesIndependent L/R modelling
- 3 optionsSources
- 48 hFirst-article delivery
06 / Design service
From impression to finished part,
a complete design service
We handle impression scan data, structural modelling, tolerance confirmation and first-article trial fitting. First articles ship in 24–48 hours for assembly validation and acoustic tuning; once the revision is approved the same process scales to 10–500 units.
01Impression / data
Scan intake and cleanup
02Modelling
Chamber, tubes, assembly features
03First article
Sample validation in 24–48 h
04Small batch
Scale to 10–500 units on the same process
If 2D drawings are needed to confirm tolerances, or material certification is required, state it with the order.
FAQ
Seven questions we hear before most orders
Concrete methods and numbers from real projects beat adjectives.
Which materials can be used for ear-canal contact parts?
For parts contacting skin or the ear canal we recommend a medical-grade resin intended for biocompatible use, with the contact area and wear duration stated on the order. We supply batch and certification documents; final compliance depends on your target market's regulations.
What is the smallest printable feature?
XY projection pixels are 22 μm, with reliable detail around 0.15 mm; minimum through-hole 0.4 mm and minimum stable wall 0.6 mm. Below these values parts are not impossible, but yield and consistency drop, so we validate with a small sample first.
How long do samples take? And batches?
Standard parts ship a first article in 24–48 hours depending on height and finishing; 10–500 unit batches typically take 3–7 business days. Rush orders can be slotted in.
Which file formats do you need?
STEP or 3MF preferred (keeps solids and assembly data), then STL and OBJ. Include 2D drawings or notes for assembly relationships, tolerances or surface requirements.
How do I choose layer height? Is 25 μm always better?
25 μm gives finer layer lines and smoother curves, but doubles the layer count and print time. For most hearables parts 50 μm balances detail against efficiency; reserve 25 μm for sound tubes and mating faces sensitive to surface continuity.
Will surfaces show layer lines? Can they be polished?
Photopolymer parts still show fine layer lines on curved surfaces. The standard route is sanding plus blasting for a uniform matte finish; clear parts add step sanding and polishing. Polishing is manual work and is itemised in the quote.
How is pricing calculated? Can I sample before a batch?
Pricing combines material, layer height, finishing tier and quantity. You can validate assembly and fit with a single part or small batch, then scale on the same process; no tooling-type fees are charged again after first-article approval.
News and insights
Project reviews and process notes
Concrete methods and numbers from real projects beat adjectives.
Case Studies
How a six-driver one-piece chamber was delivered
Six balanced-armature drivers, a crossover board and resistors inside one chamber — without losing the unibody look.
Case Studies
Clear chambers and internal colouring
Left/right consistency, surface quality and colouring were the client's three priorities in this project.
Process guide
Setting layer height, tolerance and plate layout
Is 25 μm always better? Which parts justify high resolution, and where 75 μm is more cost-effective.
Contact us
Send your requirements,
proposal and quote within one business day
Send the part's application, quantity and accuracy requirements, and we will reply with recommended material, finishing tier and lead time.
- zyang6102@gmail.com
- Business hours
- Mon–Sat, 9:00–18:00 (CST)
