Golden opportunity: How 3D printing brought a Bronze Age gold bangle into the present

"Replicas help break down the barriers to access."

by

It’s a story of collaboration nearly 3,000 years in the making; a solid gold arm band, passed through hands and machines the world over, and back to a small museum in Cumbria, UK.

In a first discovery of its kind for the area, The Beacon Museum’s Prehistoric and Bronze Age section in Whitehaven holds a rare gold C-shaped arm ring thought to date back to 900-700 BC, uncovered by a local detectorist in 2019, and acquired by the Beacon Museum and Tullie House in Carlisle. Now, a project that covers thousands of miles, and tools that would only arrive a few millennia later, is bringing this artefact to light for a new generation.

“The skill involved to create the solid gold arm ring dating back from 900-700 BC would have been extremely well practiced,” Alan Gillon, Learning and Exhibition Engagement Manager at The Beacon Museum told TCT. “There has been very little Bronze Age material discovered to date in the West of Cumbria making this artefact very rare.”

This unique find led Gillon to approach Zoe Crossan, Lab Engineer at The Bus Station Maker Space in Whitehaven to support the 3D scanning and 3D printing of a set of replicas that could be displayed at both museums. The piece, Crossan recognised, would require the most intricate of details to be captured, so she brought on board Andrew Allshorn, founder of AM consultancy AT 3D-SQUARED and ADD3D Solutions - the latter established to promote 3D printing in Cumbria - to help.

“When Andrew had created a successful scan, I produced a couple of high-res resin 3D prints on our ProJet MJP 2500 Pro,” Crossan said of the project’s first steps. “Andrew and I decided to make the print hollow so that we could experiment with filling it with metal powder to try and get it as close as possible to the whopping 386g weight of the original.”

The plan was to create four replica metal bangles, two per museum; one for display and a second as a hands-on tool for tactile learning.

“Tactile learning is key to bringing the past alive. Object handling allows people to get as close as possible to experience items that they wouldn’t get the chance to hold normally,” Gillon said. “From a sensory perspective, replicas help break down the barriers to access.”

The density was a crucial element of the replica's tactility. Printing directly in gold would be too costly, but tungsten, sitting at a similar weight, proved a suitable alternative. So Allshorn put a call out to the industry for a collaborator with the ability to print in this material. With no budget, it wasn’t exactly an easy win, until Olaf Diegel, Professor of Additive Manufacturing and Co-Director, Centre for Advanced Materials Manufacturing and Design at The University of Auckland, who had already been working on cultural preservation projects in New Zealand, stepped in with an idea.

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“We have recreated several Maori musical instruments by CT scanning and laser scanning them, and 3D printing reproductions that kids could handle and play with so they could experience the culture first-hand,” Diegel said. “The original instruments were precious family heirlooms that could not be handled by kids because, if they dropped them, the instrument would be gone forever.

“So, when Andrew contacted me about the bronze-age bangle, this was a perfect opportunity to put our skills to the test to see if we could help to reproduce it as accurately as possible, but without having to use expensive gold, so that kids at the museums could touch and feel the bangle.”

Allshorn sought permission to send over the 3D scan data to Diegel’s lab at the university where the hollowed-out design was printed on an EOS M 290 metal powder bed fusion system in maraging steel. Several iterations were produced to get the surface finish as close to the original as possible.

“The toughest part of replicating them was actually to do with the small dimples that cover the bangle,” Diegel explained. “No matter which orientation we printed the bangles in, there was always going to be sacrificial support material at the bottom of the bangle which, in turn, made it more susceptible to accidentally losing the dimples. As it turns out, though, on the original bangle there were two areas that were more ‘worn’ than the others so, in those areas, the dimples had almost completely disappeared. We used those areas as the bottom surfaces in which to put in support material and were able to get a pretty much exact reproduction of the dimples.”

Support structures inside the bangle also needed to be carefully considered to accommodate the tungsten filling. The hollow bangle was therefore supported during printing with a thin solid wall to the bottom. Once finished, the prints were sent back to Allshorn, filled with powder and capped off with brazing.

With the bands now successfully feeling like gold, the next step was to make them look like it. For that, Allshorn invited the help of Kadampa Art Studio, a facility inside Manjushri Kadampa Meditation Centre, home to the Kadampa Buddhist Temple in Ulverston. The centre designs and creates qualified statues and objects for modern Buddhist Temples and meditation centres around the world, sometimes using 3D printing to create new masters or prototypes. But it was the beautiful gold finishing radiating from the temple’s large Buddha statues and intricately painted exterior, which led to the bangles being finished with electro-brushing of gold by the studio’s volunteers.

“It was essential the bangle was fully degreased and with it being a hybrid metal, we weren't sure if it would be sufficiently passive to receive the gold,” explained Rabchog, Studio Manager at Kadampa Art Studio. “We often dip an object in copper and then nickel before electro-brushing with gold to provide a sufficiently stable surface. The 3D printed bangle substrate however, proved to be a suitable material for the gold solution to plate directly to and so the whole process was very quick.”

In some ways, it’s an incredibly local project but also a global one, made possible by a community effort with a shared passion for preservation and creative exploration of 3D technologies.

“The coolest part of the story is that you've got a group of people from all over the globe that have come together to help this little museum,” Allshorn said. “I think the community side of this is actually bigger than the project itself.”

“Time-zones and technologies don’t seem to play a big role in things if you have good people to work with,” Diegel said. “And, of course, it’s great to be working on projects that allow young people to experience hands-on aspects of culture and history that they, otherwise, would only be able to see locked away behind glass.”

Crossan, for example, is currently working on another project with Cumberland Council to produce full-colour 3D printed replicas of some of the finds from a Roman bath house archaeological dig in Carlisle.

“A member of the Uncovering Roman Carlisle volunteers said that ‘the 3D prints had made it possible for people to touch the past,’” Crossan said. “This use of 3D printing technology is an engaging way of connecting young people to their past and hopefully helps to give them a sense of pride in where they live.”

Projects like this provide more opportunities for communities, particularly younger visitors, to engage with their local history. But they can also go beyond that and help us to uncover more stories and knowledge about our past that we might not otherwise have access to.

“Historical discoveries can sometimes only be fragments of what they once were,” Gillon concluded. “3D printing and 3D scanning can fill in the missing pieces to complete the artefact, allowing people to view and experience what the object would have once looked like whether it be from recent times or thousands of years old. These new technologies are key to unravelling the past.”

This article originally appeared inside TCT Europe Edition Vol. 32 Issue 4 and TCT North American Edition Vol. 10 Issue 4. Subscribe here to receive your FREE print copy of TCT Magazine, delivered to your door six times a year.