To think about an artificial limb is to think about a person—an individual who moved, reached, worked, and lived with that device as part of their body. Prosthetic limbs are not just mechanical objects; they are tools of motion and touch, designed to connect people to their world.

Yet, when prostheses from the past are studied in museums or archives, the human connection often feels distant. Their users are long gone. The devices are typically damaged, worn down by centuries of time and exposure. They sit motionless on display or tucked away in storage—silent artifacts with untold stories.

These historical objects are rare and often the only direct evidence of amputees’ lives in premodern Europe. Written accounts from the 16th and 17th centuries are scarce, and those that survive rarely discuss what daily life with a prosthesis was like. For historians, the challenge is clear: how can these silent artifacts speak?

Thanks to modern engineering tools, a new kind of historical exploration is now possible.

At Auburn University, a collaborative team of historians and engineers set out to explore one of the few surviving prosthetic hands from Renaissance Europe: the Kassel Hand, a German iron prosthesis from the early 1500s. Of the roughly 35 similar artifacts known today, most are of unknown origin and no longer function. Their original use—and the lives of those who wore them—remain largely mysterious.

Using computer-aided design (CAD) and 3D printing, the team aimed to change that. By reverse-engineering the Kassel Hand, they created working models to test its mechanics and understand how it may have been used 500 years ago.

These 3D-printed replicas weren’t just digital experiments. They were tangible, functional tools built from inexpensive plastic—accessible to anyone with a consumer-grade printer. But before the team could share their work with the public, they needed to test how well the models held up in real-world hands.

The first major test came during a guest lecture at the University of Alabama Birmingham. The team’s historian arrived with two 3D-printed hands, excited to demonstrate the results of years of collaboration. But within fifteen minutes, both models broke.

The issue centered on the release lever—an internal mechanism that locks and unlocks the fingers. Once broken, the fingers remained stuck in position. Despite extensive lab testing, the lever had never failed like this before. The team was puzzled.

Was it a design flaw? A printing defect? Or something else entirely?

Back in Auburn, the team’s lead engineering student—nicknamed the “Hand Whisperer”—wasn’t surprised by the news.

Over two years of developing and refining the model, he had assembled and tested the Kassel Hand countless times. He had witnessed the release lever fail in the lab during component checks, even though it hadn’t failed in public before.

The problem, he explained, was not just the material (PLA plastic is brittle compared to iron) but also user technique. The original artifact’s iron parts were far stronger than plastic. Most likely, users in Birmingham had pulled the trigger too far, too quickly—something the engineers had learned to avoid through experience.

The break wasn’t simply mechanical. It was human.

With this realization, the team devised a two-part solution.

First, the engineers redesigned the model slightly, narrowing the opening where the release trigger emerged. This small change limited how far the trigger could be pulled—and, as it turned out, made the model even more historically accurate. The earlier version had included a larger opening to accommodate a previous prototype, but that extra space was no longer necessary.

Second, the historians turned their attention to instruction. Over the course of development, the team had unconsciously learned how to operate the hand properly—but new users hadn’t. To fix that, they created an instructional video, demonstrating how to use the model, operate the locking mechanism, and troubleshoot if anything got stuck.

They weren’t just building a replica—they were restoring a learning process.

Exactly one week after what the team jokingly called “the Birmingham Break,” they tested the updated models in a history classroom at Auburn University.

This time, they brought four revised hands. Before letting students handle them, they played the new instructional video. The results were clear: not a single lever broke.

The team officially launched the Kassel Hand project on schedule.

The Kassel Hand’s story is more than just a successful academic experiment. It highlights how even historical technology was deeply personal. Just as the 16th-century amputee who wore the original hand had to learn to use it, today’s users of the 3D-printed version must learn, too.

Technology—past or present—isn’t just about design and mechanics. It’s about people, training, adaptation, and practice. Rebuilding the Kassel Hand has brought two very different fields—history and engineering—into meaningful conversation. In doing so, it’s opened new doors for understanding both the past and the present.

And in the hands of those who engage with it, this ancient prosthesis has come to life once again.

By Impact Lab