How 3D Printing Cornwall engineered, tested, and manufactured 66 weather-resistant decoys for Ørsted’s Hornsea Three conservation programme.
Ørsted — Hornsea Project 3
Offshore nesting structures, Suffolk coast, England
66 3D-printed kittiwake models
Structures designed to house up to 500 breeding pairs
Black-legged kittiwakes are among the most delicate of Britain’s seabirds, spending most of the year far out at sea and returning to precarious cliff ledges each spring to breed. Over the past three decades their numbers around the UK coastline have fallen sharply, a decline driven largely by warming seas that have disrupted the sandeel and small fish populations kittiwakes depend on to feed their chicks. Changing climate patterns have pushed prey further offshore and altered the timing of the food chain, leaving many colonies unable to raise enough young to sustain their population. The species is now listed as vulnerable, and safeguarding its remaining breeding sites has become a priority for conservationists working alongside the offshore energy industry.
Since 2020, energy company Ørsted has been developing Hornsea Project 3, the latest phase in a series of offshore wind farms built in the North Sea along the same stretch of English coastline that many of these kittiwake colonies call home. As with any major infrastructure built near sensitive habitats, the development came with a responsibility to protect the wildlife it could potentially disturb, and to look for ways of giving something back to the ecosystems it now shares the coastline with.
As part of the environmental mitigation strategy for Hornsea 3, Ørsted was required to construct three offshore artificial nesting structures purpose-built to support the vulnerable kittiwake population. Each structure was engineered to house in the region of 500 breeding pairs, offering a safe, predator-free alternative to the crumbling and increasingly unstable natural cliff ledges the birds have traditionally relied upon.
Yet building a structure, however well engineered, is only half the challenge. Wild seabirds are notoriously cautious about settling in unfamiliar locations, and a bare steel platform gives a passing kittiwake no reason to believe a site is safe, established, or worth investing a breeding season in. To stand any real chance of success, the new structures needed a strong visual and behavioural incentive: the convincing impression that other kittiwakes had already made the site home. This is precisely where 3D Printing Cornwall’s expertise came in.
Ørsted required highly realistic, durable decoys to attract endangered Black-legged Kittiwakes to new artificial nesting structures off the Suffolk coast. The core challenge for 3DPC was engineering a solution that met strict biological standards set by ornithologists, while surviving the extreme wind, salt, and corrosive elements of an offshore marine environment.
Conventional decoys, whether mass-produced in plastic or hand-cast in resin, are typically built to a generic template. They lack the fine anatomical precision needed to convincingly mimic the exact posture, proportions, and subtle body language of a real, living bird — details a wild kittiwake instinctively reads when deciding whether a ledge is occupied and safe. For a species this cautious, an unconvincing decoy is often worse than no decoy at all.
With construction of the nesting structures completed in spring 2023, Ørsted needed a solution that would be ready in time to give the new colony the best possible chance in its crucial first breeding seasons. That meant working to a tight timeline while still delivering a level of anatomical accuracy that off-the-shelf decoys simply couldn’t match.
Starting from a 3D scan of a taxidermy kittiwake, we modified the CAD geometry to ensure optimal printing while meeting the strict anatomical requirements of the BTO and RSPB.
Selected 100% recycled PETG for its excellent UV resistance, layer adhesion, and durability against saltwater, perfectly aligning with the project’s ecological goals.
Engineered a bespoke mounting mechanism using Neodymium magnets. We calculated and tested the exact pull-strength required to secure the decoys to the metal platforms in gale-force offshore winds.
Designed the internal geometry to prevent water ingress. Finished the parts with marine-safe paints to ensure long-term visual fidelity and protection against the elements.
3DPC’s in-house capability spans SLA, SLS and FDM printing, giving the team the flexibility to choose whichever process best suited the decoys’ anatomical detail, surface finish, and offshore durability requirements, rather than being locked into a single technology. That versatility proved essential in balancing fine feather-level texture with the toughness needed to survive a North Sea winter.
In the production phase, 3DPC successfully manufactured 66 identical decoys, maintaining strict dimensional tolerances and quality control across the entire batch to ensure every single unit was ready for offshore deployment.
— Michael Hunt, 3D Printing Consultant, 3D Printing Cornwall
Before deployment, the decoy design was reviewed and approved by ornithologists at the British Trust for Ornithology (BTO), Natural England, and the Royal Society for the Protection of Birds (RSPB), ensuring every anatomical detail met the standard required for genuine biological authenticity.
The decoys were successfully deployed on the offshore structures, with the magnetic mounts holding firm in rough conditions. In the 2024 breeding season, just months after installation, a real kittiwake pair nested next to our decoys and produced a chick—a massive early success for the conservation effort.
The decoys were placed across two of the three offshore nesting structures, positioned to encourage real, wild kittiwakes to investigate, settle, and ultimately begin nesting alongside them. Each structure was designed with alternating rows, a layout that not only suits the birds’ natural nesting behaviour but also gives ornithologists clear sightlines for ongoing monitoring without needing to disturb the colony.
Remarkably, in late August, just one breeding season after the structures were completed, a kittiwake chick hatched close to the 3D-printed decoys. Colonisation of a brand-new nesting site can typically take several years, so a confirmed hatching this early is a striking result. Ørsted’s team described being surprised, but delighted, that a chick had already been born, and hope it marks the first step toward a fully established, self-sustaining colony.
Ornithologists from the partner conservation organisations will continue to monitor the structures in the years ahead, tracking further nesting activity and colonisation as the site matures.
Recycled-plastic decoys produced
Breeding season to first chick hatched
Breeding pairs each structure can support
Projects like this highlight a role for additive manufacturing that goes well beyond the industrial prototyping and product development work most people associate with 3D printing. Precision, repeatability, and the ability to replicate fine natural detail at scale are exactly the qualities needed to support a genuine ecological outcome, not just a commercial one.
For 3D Printing Cornwall, the Hornsea 3 kittiwake decoys represent a project the team is genuinely proud of: a piece of technical craftsmanship, grounded in careful research and scientific validation, that has already contributed to a real, measurable biodiversity result on the Suffolk coast.
As offshore wind continues to expand around the UK, the demand for thoughtful, evidence-based environmental mitigation is only likely to grow — and 3DPC is proud to have shown what precision manufacturing can offer when applied to conservation.
From marine conservation to industrial prototyping, we engineer additive manufacturing solutions that solve complex challenges.
Ørsted — Hornsea Project 3
