Last year, I was talking with a friend of mine about some of our "holy grail" projects. I told him that it was one of my dream builds to make a T-800 Endo Arm, as an actual prosthetic for an amputee. You know the scene - in T2, Arnold cuts off the skin of his left arm to expose his robotic endoskeleton.
I told him how it would be a dream project to build an Endo Arm like in this scene, for someone who is missing a limb. I've met or been made aware of a few people over the years who used their unique body attributes in their costumes, but I never had the chance to connect with someone.
He said he wanted to introduce me to someone. This is Laura.
Laura is a left arm transradial amputee - meaning that she is missing her left arm below the elbow - since birth. She's also really into cosplay, and living in Atlanta, she has been a "featured zombie" on The Walking Dead. You've probably seen her in the shambling hordes.
After we met I told her about my idea and what we could do, and she was enthusiastic. I felt really lucky because this really was one of my dream projects. She said she had done a few costumes in the past that incorporated her arm, but nothing really to the scale of what we planned. The idea was to 3D print a CAD design for the Endo Arm and possibly wire it up with some sensors and servos to make the fingers open and close. It was going to be a fun and really challenging build, and I was really looking forward to getting it started.
And then, Mad Max: Fury Road came out and changed everything.
You might have read Laura's blog post on her Tumblr that went viral a couple weeks after Fury Road hit theaters. Needless to say, Laura connected with Furiosa on many levels. Most importantly, she decided she had to cosplay as her.
Cosplay as her immediately, that is. This is her at MomoCon, a convention here in Atlanta, only a couple weeks after Fury Road's release. Needless to say, she was excited.
We had a short conversation and I asked her permission to build her the Furiosa arm as a real actual prosthetic, much like we were going to do for the T-800 Endo Arm and she couldn't have been more thrilled. Our plan was to finish it for Dragon Con 2015. Needless to say, I was excited too.
During our planning for the Terminator Endo Arm project, I took a 3D scan of her using an Xbox Kinnect and a software called Scannect. It allows you to easily get a rough 3D scan of someone or an object. It's not high enough detail to look photo realistic, but it's enough to get basic proportions. I use this myself to scale Pepakura files and do other digital sculpting. We tried getting a 3D scan of her arm and the results were alright. Really it was just enough to use for scaling and "subtracting" her arm from the Endo Arm model.
When we shifted gears to Furiosa, I decided the first thing to do was to get a plaster cast of her arm - The prosthetic would have to actually fit her, and there was no way for me to "try on" the prop myself while building it. After an afternoon at the shop, I had one of the weirdest casts I've ever made, but it was exactly what we needed!
At this point I got a lot of help from @MrGreene who took a higher detail 3D scan, and assisted by creating the 3D model used for the build. Laura and I agreed that we should 3D print the arm to cut down on as much weight as possible. I was worried that if it was too heavy that she wouldn't be able to lift it, or she would become fatigued after wearing it for a short period.
The pieces were 3D printed on my home 3D printer, as well as the printers at Freeside Atlanta, the non-profit hackerspace that I work out of. After a few long prints, everything was ready to be cleaned up and assembled.
The process of cleaning up a 3D printed prop is pretty simple - rough sand the surface to get rid of some of the print lines, then (in the case of an ABS print) use "ABS sludge" - a thick mixture of acetone and ABS - to coat the surface. This acts like a body filler and will help fill in the remaining gaps, but as the acetone evaporates, the ABS bonds to itself, so you have a single rigid object. The part is then sanded with a finer grit sandpaper, and coated in spot putty to fill in any remaining pits or print lines. After that dries, the excess is sanded off, and then primed for painting.
After 2 days of work, that leaves the project where it is now. I'll be finishing up filling the gaps where the fingers were attached, and prepping the main body of the arm for paint. I'm going to start sourcing some of the mechanical bits - springs and push rods for the supporting rods of the arm - so everything can be assembled. I also am going to source the tubes running from the shoulder pad down to the arm, and we'll be doing the leather work next weekend.