Author: Michael Campos

Michael Campos with his son, Carter.

My son, Carter, was born without his right hand. Who would have thought his innocent request that I build him a hand would have turned into such an incredible journey? We have lost count, but we have built an estimated two dozen 3D printed helper hands for children around the U.S. and even a few overseas. It is hard to believe Claws from Carter is just a little over a year old.

After our story began being published on websites around the world, things really took off. We have had engineers, doctors, designers, web developers and 3D printing hobbyists reach out to us wondering how they can get involved. Carter’s face, together with his e-NABLE hand, has been seen in more countries than I have been able to count. Carter even made the front page of Reddit!

Helping children like Carter is the inspiration between the Berkeley students’ work. “It got me a little choked up,” his father said.

An assistant professor in Mechanical Engineering at the University of California, Berkeley reached out to me in the summer of 2017; she was curious about our experiences building helper hands. After speaking with Dr. O’Connell, we agreed to base a portion of her mechanical engineering course around Claws from Carter and what those with a limb difference have requested or might find useful.

When the school semester began, I was given four teams of students, each to come up with their own unique design. We had our initial video conferences to introduce ourselves and discuss goals for their projects. We assigned one team for a weightlifting device, one for a task-specific universal attachment device, and two teams to develop bike handlebar adapters. When I was sent some of the initial designs, it hit me that these students were were working toward bettering people’s lives, people like Carter. It got me a bit choked up.

Throughout the semester, the teams bounced different designs off of me via video chat, email, or group texts, and I provided them with feedback and ideas of my own. Eventually they began sending me STL files, which I printed out get a hands-on feel for the devices. With every video chat and design improvement, our excitement grew. The semester began to wind down, and I couldn’t believe how fast it went by; it did not work like that for me when I was in school. I got the feeling that some of the students were sad to see the semester coming to an end as well.

The team’s final designs, although not finalized for public release yet, were amazing. I printed everything out of Matterhackers NylonX filament using their Pulse printer. Though depending on the printer it might require a few upgrades (all-metal hotend, hardened nozzle, heated bed), this material is very easy to print with and provides great strength and durability, which are important when it comes to these projects.

Image A: Handlebar adapter. Photos courtesy of Dylan & Ricky at Matterhackers Inc.


The first handlebar adapter is a spring-loaded quick-release design (Image A). It works in such a way that if the user is going to take a spill, they can release the device from the handlebar instead of getting trapped while the bike goes down. It also has a swivel hinge within it which allows adjustment for different angles. Aside from the printed parts, the required hardware can easily be found at a local hardware store or online.

Image B: The second handlebar device with a swivel function can be printed in one piece instead of separately.

The second handlebar device also has a swivel function, but instead of the hinge being printed separately it has the ability to be printed as one piece (Image B). It was impressive watching this one print. This is a modular design which allows the length to be extended simply by adding another piece.


Image C: Task-specific device with painter’s pallet attached.

Next, we have the task specific device (Image C). Here you can see it is using the painters pallet attachment.

The attachment design is very simple. There is a hexagonal socket on the cuff that the pallet easily slides into and a pin to secure the attachment to the cuff. This will allow for quickly changing in and out different attachments depending on the activity being performed. When finalized, my hope for this is to hold a design challenge for others to come up with all sorts of different task specific attachments. Cool, right?

Unfortunately, I was not able to complete the weightlifting device because I could not find the required strap. It is still a work in progress, though, so keep an eye out for it.

After a successful and exciting semester working with U.C. Berkeley, we have decided to continue the partnership indefinitely! We are already preparing for next semester, which is going to be starting very soon. I had a blast working with my teams; they came up with some excellent designs, and I can’t wait to see next semester’s devices and improvements!

Categories: Minds at Work

1 Comment

Jim Frey · January 27, 2018 at 1:41 pm

I don’t believe your school experience was anything but wonderful! Good job Mike!

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