David Aguilar was nine years old when he assembled his first prosthetic arm from LEGO bricks. Born in Andorra with Poland syndrome, which left him without a right forearm, Aguilar faced daily challenges and frequent bullying at school. He saw that the toy blocks that comforted him could also provide the basis for a practical solution to his physical limitations.
Aguilar’s fascination with LEGO began at age five, when he received his first set. The blocks soon became a refuge from the isolation he felt among his peers. Four years later, he tried attaching one of his creations to his arm and saw the potential to turn a childhood toy into a functional device. His first prototype, built from a LEGO ship set, was far from perfect: it lacked durability and full functionality. Still, it showed that his idea was possible and gave him a new sense of confidence.
From Prototype to Functional Arm
It took Aguilar nearly a decade to turn his early experiment into a fully functional prosthesis. At 18, he completed the MK-I, a prosthetic arm built from LEGO Technic helicopter parts. The device had a red frame, a movable elbow joint and a gripping claw activated by flexing his upper arm. Unlike his childhood attempt, the MK-I let him perform everyday tasks and even support his weight during push-ups. Its added functionality marked a step forward in accessible prosthetic design.
In January 2017, Guinness World Records officially recognized the MK-I as the world’s first functional prosthetic arm made from LEGO. The distinction went to the model Aguilar built at 18, not his first childhood prototype. That detail reflects years of development and refinement. Guinness World Records featured his story again in January 2026, around International LEGO Day, presenting Aguilar’s journey as an example of ingenuity meeting necessity.
New idea Driven by Experience
Aguilar continued beyond the MK-I. Over the years, he developed five different models, each more advanced than the last. The MK-V, for example, included five movable fingers, with sensors and motors linked to a pulley system. Subtle movements of his upper arm controlled it. He also shared a free video tutorial on building and programming this version, making his work accessible to others facing similar challenges.
His focus on affordable solutions led him to study bioengineering and design low-cost prosthetics for others. One impressive project was for Beknur, an eight-year-old boy born with underdeveloped limbs. Aguilar built two prosthetic arms for him from LEGO parts, at a cost of just 15 euros each. One arm had a foot-controlled claw, while the other included an electronic pointer for touchscreen devices. The designs earned two additional Guinness World Records in August 2021 and showed the practical impact of Aguilar’s approach.
Expanding Impact and Social Commitment
Aguilar’s work has reached beyond personal new idea. The World Intellectual Property Organization reports that he launched the HandSolo brand and dedicates part of its profits to organizations and projects supporting people with disabilities. His efforts have become a reference point for accessibility and technical education, while also advancing workplace inclusion. They show how individual creativity can lead broader social change.
Aguilar’s story shows that solutions to complex problems can emerge from unexpected places. By turning a childhood toy into a tool for independence, he changed his own life and created new possibilities for others facing similar obstacles.
