“Don’t tell me you’re trying to 3D print my engagement ring”

Like all other artforms, the process of jewelry making is a work in progress, constantly evolving and adapting to new techniques and technologies. From shells and stone that have been fashioned into beads, to lab-grown diamonds and laser-cut gemstones, it is no surprise that jewelry and technology have gone hand-in-hand. Modern technology continues to revolutionize the jewelry industry, pushing the boundaries of traditional design and manufacturing.

So when Tanner Aikens set out to fashion his own jewelry, it was only natural that he turned to 3D printing. With plans of proposing to his girlfriend of six years, Aikens (M.S. ’25, B.S. ’24) was inspired by his graduate additive manufacturing course at CMU to craft several pieces of custom jewelry to match the engagement ring he picked out.

3D printing has been used in jewelry making since the 1990s, but Aikens’ specific design and approach had never been done before, making his project novel and one-of-a-kind. Aikens and his girlfriend are mechanical engineers by trade, so it was only fitting to fashion her a necklace in the shape of a helical gear. As it turns out, the process of making this gear-shaped pendant come to life was much more difficult than he first thought.

“Originally, I thought it would be an unlimited design space because 3D printing is pretty flexible,” Aikens said. “It turned out to be a lot more difficult than I thought it was going to be because I wasn’t just thinking about the functionality of the piece but also its appearance.”

Aikens’ jewelry is made from titanium, which provided his pieces with the necessary durability to withstand wear and tear over time. However, this extra strength made it especially difficult to set a gemstone compared to softer, more malleable metals like gold, silver, or platinum. 

Instead of setting a gem with traditional prongs, Aikens planned to tension set his gem, which is held in place using the pressure of the titanium. Although titanium is traditionally considered a difficult material to work with, its high elasticity, relatively low cost, and exceptionally high stiffness made it an ideal choice for Aikens’ project. Since his jewelry is custom made, Aikens had to buy his own gemstones, which included a mined aquamarine, a handful of cubic zirconias, two lab-grown sapphires, and a bag of moissanites, an alternative to diamonds. 

To manufacture his pieces, Aikens collaborated with Incus3D, a company that produces industrial 3D printers for metal manufacturing, and CMU’s Additive Manufacturing (AM) Laboratory. Incus3D uses lithography-based metal manufacturing (LMM) technology, a 3D printing process that uses light to shape a photosensitive resin and metal powder into high resolution parts with fine detail.

Coincidentally, CMU’s ExOne Innovent+ Binder Jet uses a similar technology, just at a lower resolution. The Next Manufacturing AM lab doesn’t typically allow personal projects to be printed using their machines, but the lab personnel already had a training print scheduled, which allowed Aikens to have a few of his designs printed on campus using stainless steel instead of titanium.

In binder jet 3D printing, powdered materials held together by a binder, commonly referred to as green parts, are joined together by heat in a process called sintering to create a solid, 3D object. Sintered parts, however, can shrink when they are fired into their final form. This shrinking, also known as densification, meant that Aikens’ final products would be about 15–20 percent smaller than their original design measurements.

To compensate for this shrinkage, which would make gem setting even more challenging, Aikens decided to drop the gemstone into the green part, allowing the metal to shrink around the gem in a process he coined to be “shrink setting.”

“As far as I could tell, nobody in the whole world has ever tried this before, or at least never succeeded, and I found out why,” Aikens said. “The gemstones, specifically the cubic zirconias, don’t really interact well with binder as it vaporizes. It turns out there’s a lot of weird chemical reactions that happen at roughly 1,300 degrees Celsius, which is the sintering temperature of stainless steel. So, I ended up with discolored gems and oxidation problems.”

Despite the gem discoloration, Aikens walked away with one pendant from the binder jet and received even more titanium pieces from Incus, including an earring. Moving forward, he plans to order more gemstones to accommodate the shrinkage of the pendant from Incus. And while he still has more work to do before presenting the pieces to his girlfriend, Aikens’ expectations of what he was able to accomplish and learn were beyond exceeded.

I think it’s good for mechanical engineers to know how certain materials interact and why you pick different materials for different purposes.

Tanner Aikens

“It was a huge journey, and I learned so much about design and materials and process optimization. I definitely think that this project both expanded my horizons of what I could learn and also helped me learn the material from my classes better,” Aikens said. “I think it’s good for mechanical engineers to know how certain materials interact and why you pick different materials for different purposes. I think that will come in handy in my career later on, maybe not immediately, but just having an intuition for these materials and why we use them is really helpful.”

Despite the gem setting struggles and discoloration, arguably the toughest challenge he faced was not in the design or printing process, but keeping the project a secret.

“When I was shopping for gemstones, I asked my girlfriend her preferences, and she said, ‘Don’t tell me you’re trying to 3D print an engagement ring.’ I responded, ‘Of course not, I wouldn’t be using such cheap gemstones.’ So that’s how the secret got out,” Aikens said. “I like telling people what I’m working on, so eventually I just spilled the beans.”

Aikens graduated from CMU through the Mechanical Engineering Department’s integrated master’s/bachelor’s program. He currently works at Ryobi Power Tools as robotics engineer.