The man behind a Georgia boy’s “Star Wars”-themed prosthetic arm is 3-D printing enthusiast John Peterson, who just so happens to live in the same town as the youngster. Employed at General Dynamics, Peterson assembled his own 3-D printer over the past year, using parts he purchased online. While surfing the net, Peterson came across e-NABLE, a group that creates open-source designs for prosthetic arms and hands. They quickly matched him with Liam Porter, 7, who was born with only a very small portion of his left arm.
Following up on our previous blog post about the project, Not Impossible Now spoke with Peterson about how he crafted his unique sleek-looking clone trooper arm at Liam’s request over a period of a few months and at a cost of just over $100 for materials. The look on the little boy’s face when he was presented with the completed arm, he says, was priceless. Of course, Liam knew something was up as Peterson had to take precise measurements to be sure the plastic limb was a perfect fit. He also made the arm so that as Liam grows, he can replace parts easily.
NIN: How long have you been a 3-D printer hobbyist?
John Peterson: It hasn’t even been a year yet.
How did you get into it?
Peterson: I knew it was evolving. 3-D printers still are kind of expensive so I decided to build one from the Prusa i3 (iteration 3) model. I bought all the parts off eBay and put it all together and it’s working pretty well.
What was the first thing that interested you?
Peterson: As I was building it, I saw all the cool things that people were doing with it like building quad copters and robots. One thing I saw was InMoov, where you can get all the plastic parts for a robot. You have to put all the motors and stuff inside it. I saw people making arms and things with the InMoov models. Some of them were making them with controlled arm movements like muscle movements. So I kind of looked at it and went, “That’s cool.” And then I found e-NABLE.
How did you two get matched with Liam by e-NABLE?
Peterson: I filled out a form indicating my interest in wanting to make a prosthetic arm. For arms, you really have to be local because of certain sizing that you have to do. If you happen to be local to somebody who needs a hand or an arm, it’s always better so they try and match you up locally if they can, or as close as possible.
How did you make the arm?
Peterson: There are two ways to do it. Both are pretty cool. You make the arm’s cuff piece, where Liam’s stump would go into. You make a 3-D scan of it and make a solid piece and put the two pieces together, and merge them and then subtract the arm. It’s like a negative mold, but done in the computer world. With that you still have issues like plastic next to the skin. You wouldn’t have a mold per se, which is the plastic against skin. So you’d have like a gel sock that you put on it. The possibility of that being an even better fit would be good. So that’s one way of doing it.
The other way is that you would print the part out as you would normally print the part out. Then, you have a silicon mold, and you have the (recipient) put their arm in the mold for about 30 minutes, and when they pull it out it congeals and becomes a perfect fit.
When did you meet Liam?
Peterson: Around October.
Did he know what you were going to make for him?
Peterson: He knew he was going to get an arm. He just didn’t know he was going to get it in a big presentation. When we did the silicon mold, the arm was in pieces. It wasn’t a fully functional arm. I had a demo arm that was orange that he really couldn’t use. Until it’s custom-molded, it won’t work right. So when he (sat for) the silicon mold, he didn’t know how well it was going to work out until he picked up that cuff for the first time.
How did the idea of the clone trooper come up?
Peterson: I like themes. So I asked Liam what he liked, what interested him, and he immediately said, “Clone trooper.” So I said, “Okay, we’ll do a clone trooper arm.”
How long did it take to make?
Peterson: You can print it out pretty quickly, but the arm is a little more complicated. I had a bit of a learning curve, particularly like what silicon mold to get, where to do I get it from, how much is it and all that kind of stuff. But with all that knowledge in my head now, I could probably knock it out in a couple of weeks. When you’re doing it the first time, you have to get everything put together in your head. With 3-D technology, there’s not a lot of (resources). There’s definitely help with e-NABLE, and there are lots of good people there you can ask questions of but sometimes those people aren’t local and so you have to chat with them over the phone for a direction and just follow that direction out.
Who covers the cost of it?
Peterson: The Augusta Chronicle said it was about $300. It’s actually closer to $120, give or take. That surprises a lot of people; they think it would cost more. Plastic rolls cost about $22. I know there are more expensive plastic rolls out there, but truth be told, if they work, they work. I have a good supplier on eBay that I get the plastic from. They’ve never let me down as far as the quality goes.
Obviously kids grow. How long will the arm last before Liam needs another one?
Peterson: I guess it depends on how fast he grows, but all we have to do for him is take the silicon mold out and then remold it, recast it. And, within an hour or so, he’d be ready to go again for another six months. The only issue there is the length of the arm. That aspect is debatable. Some kids actually don’t like the longer arms. Some don’t want it extending, they just want the hands as close as possible. The cool thing about 3-D printing and people like myself that make these arms, we get to choose how the parts are going to look. We can say, “Okay you don’t like that. Maybe we can do something else.” The length of the arm is no more than changing the PVC pipe that you can find at any home improvement store. It’s only a few bucks and they’re very strong. So you just take out the old pipe and put the new one in. You put the strings back in and — boom — you’ve got a new arm. It’s just a little bit longer.
How did the 501st Legion get involved?
Peterson: When I started working on the arm, I went to Atlanta for a Maker Faire with part of Liam’s new arm. I saw some people with 501st. One of the members, Jen Belgin, is a costume designer. I asked her if she would do some design work, specifically paint the arm and make it more clone-trooper-ish. I’m sure I could have tried it myself but she is an artist. I knew if I wanted it to really look like a clone trooper arm, I needed a professional to paint it. Not only that, but she made a helmet to match the arm for Liam.
When you saw his face when he got his arm, did it make all the time you spent working on it worth it?
Peterson: It was worth it long before then. It’s nice to see that reaction. Definitely.
Do you feel like a hero?
Peterson: It’s pretty cool. It’s nice to change a life in a positive way.
Are you working on other projects with e-NABLE?
Peterson: Liam has come up with all kinds of wonderful ideas. Since then, I’ve made a couple of new parts. It’s kind of cone-shaped and goes over the PVC pipe so you really can’t see the PVC pipe anymore, or very little of it. And I thought, what if I put a rail system on this and start putting in a couple extra devices. That was just off the top of my head. I talked to a few people about it. I really think rail systems can do a lot of things. I was thinking about if I only had one arm, I could probably do a lot of things well, but what could I not do well. Cut a steak or eat waffles — that would be kind of difficult because I wouldn’t be able to keep the steak on the plate while I was cutting it. So I came up with this clamp that I made in the virtual world. I printed it out and it worked okay. So Liam can now hold a fork with his arm. The other day he was able to cut waffles using his prosthetic arm so that was pretty great.
Do you stay in touch with Liam and his family?
Peterson: Oh yeah, because he’s going to grow and as he grows I’m going to do more things for him. Really, the cool thing about this relationship is Liam can come up with ideas for improving the arm. With the rail system, kids don’t care that it doesn’t look like a real arm because they want it to be cool, the cooler the better. To them it’s like, “Hey, I’m a superhero! I’m a Clone Trooper.” The rail system is really something that’s been missing from the prosthetic industry for a long time. You can have replaceable tools. What if I need a tool that does XYZ, they don’t have an arm that can help me do that. But now I can slide this tool on and do that.
We (makers) do these little video chats about the rail system, and we said if we’re going to do that, we’re going to have to come up with a utility belt like Batman. It’ll be an arm belt.
It seems like things that were once considered only in the realm of science fiction are beginning to happen.
Peterson: With a 3-D printing, it can happen a little bit quicker because in order for something miraculous to happen, until recently, a large corporation had to have involvement. They had to produce the product and they had to have a need and they had to sell it. With 3-D printing, we don’t need that. Anybody can choose to make the world differently and do it very quickly and for low cost.
Watch Liam receive his clone trooper arm in the The Augusta Chronicle’s YouTube video below:
Top photo courtesy of John Peterson