Group Provides Free 3-D Prostheses

Comprising artists, makers, teachers and tinkerers, eNable — a nonprofit organization — is designing and developing 3-D printed upper limb prostheses, and giving them to amputees in need, for free.

These mechanical prosthetic devices, or mech-ens, feature movable plastic digits controlled by any movement the user has available, and are built exclusively using resources within the eNable community.

That community is made up of members who custom design for individual needs, create small parts or entire devices, guide people through the building process and pair amputees with builders who produce the devices.

eNable launch

The idea of a 3-D printed hand originated with Ivan Owen, a Washington State inventor, and Richard Van As, a South African carpenter who lost his fingers in a work related incident. In 2012, using a 3-D printer, the two collaborated to create the RoboHand — an open sourced prosthetic hand — and documented their success via a YouTube video.

Through the comment section of that video, Jon Schull, PhD, researcher at the Rochester Institute of Technology, realized builders were spread across the globe who were capable of creating 3-D prostheses, as well as amputees without the means to obtain a prosthesis.

He saw a need to bring these two groups together, which led him to create a Google map where individuals with 3-D printers could ping their locations, and amputees in search of prostheses could connect with them.

“He wanted a giving community like this to exist for a while, and saw an opportunity in RoboHand’s video,” Nick Parker, open source hardware enthusiast and longtime member of eNable, told O&P Business News.

As the map grew more populated, a Google+ community was created to better connect builders, and has since grown into a group of nearly 600 individuals looking to innovate and improve upon the original open source design.

“We have volunteers from just about every walk of life: medical professionals, university researchers, resellers and ordinary people who volunteer their time,” Parker said.

“Starting out, we expected to have a list of users with no builders nearby, a list of builders with no users nearby…it turns out the first list didn’t exist,” he said. “We are always able to track down local hobbyists willing to help.”

Building a mech-en

To create an eNable mech-en, members start off by generating an upper limb prosthetic blueprint and posting it as an open source design in the Google+ community. After it is altered and improved by other members, the final design is used to begin the building process.

The 3-D printers use a process called fused filament deposition, which Parker described as a tiny hot glue gun, which is navigated by a computer along a predetermined pattern.

“The machine starts by drawing a shape on the build plate and coloring it in with lines of plastic about a half millimeter wide,” he said. “It then draws similar shapes on top of that first one, over and over, until a whole object has been built from layers of plastic.”

The standard design of these devices, including the Cyborg Beast and Talon Hand 2.0, capitalizes on any existing motion in the user’s residual limb by using a pulley system.

“In almost all cases that motion is the flexion and extension of the wrist,” Parker said. “We run strings around pulleys at whichever joint we’re using and use the movement of those strings to actuate the mech-en. That means running the strings up the underside of the fingers so they curl [around the desired object] when pulled.”

In cases where there is limited or no movement available in the wrist, the motion of the elbow is used to pull the strings and a locking mechanism is added, enabling grip capability without restricting elbow movement.


According to Parker, the mech-en devices have been well received by users, as well as those close to the amputee community.

“Everyone from our users, to industry professionals, to laymen have been incredibly positive about eNable,” he said. “I guess there isn’t much to take issue with in providing quality-of-life improving devices for free.”

Cost efficiency

An industry standard prosthesis could run up to $10,000, whereas an average mech-en costs around $20 to build, and more complex designs can cost about $60, Parker said.

As a nonprofit organization, eNable never sells the devices, but instead guides users to create, and prints no cost parts for those without the means to create.

“Most builders just pay for the materials themselves and never ask for any sort of reimbursement,” Parker said. “I have never used the word ‘dollar’ in communication with a family I am building for. I think seeing the life changing effects of these devices makes people forget about the small sums of money.”

The low cost is a big advantage, particularly for young children who could grow out of a prosthesis, those with no insurance coverage for an industry standard prosthesis and individuals in developing countries who are more susceptible to environmental injuries.

Time commitment is one of the minor drawbacks in running a nonprofit organization, but Parker said that is not much of an issue since there are numerous members devoted to making a difference.

A look ahead

Mech-en prostheses are a viable option for some; however, they are purely mechanical, unregulated medical devices and should not be assumed to be perfect, Parker said. For example, there is constant loss of strength to friction in the cabling.

Although they are not yet comparable to advanced myoelectric prostheses, more studies are being conducted to improve overall functionality, such as characterizing grip loss and looking into easy, cost efficient ways to eliminate it.

Aspects such as locking parts of the hand to allow pointing and pinching, long-term effects on muscle development and closer analysis of the device’s utility are also being researched.

Parker believes mech-ens are moving toward more advanced locking systems and devices that are human driven in both directions, without any elastics. He predicted they will become an increasingly popular option among children and have a huge effect for people in developing countries.

“I think our biggest impact will be in developing nations…particularly places like the Democratic Republic of Congo, where amputees are common,” he said. “Extremely low cost devices like this will have a massive impact.”

Parker said eNable will continue to build mech-ens for its community, and he believes 3-D printed prostheses will become a future standard, serving as an alternative for individuals who cannot obtain an industry standard prosthesis.

“I see eNable scooping up the cases upper limb prosthetists can’t take. If it is within the capabilities of our members to build, we build it.” — by Shawn M. Carter

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Disclosure: eNable is not officially affiliated with the RoboHand Project in South Africa, but instead builds off their work and that of others.

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