Learn a new fabrication technique from DIY prosthetics builders

This is a screenshot from a video tutorial on making your own prosthetic parts from 2-liter soda bottles. The opaque white part is a mold made of plaster. It’s a representation of the wearer’s limb, and provides the hard, heat-resistant form necessary for this manufacturing technique. You can see the clear plastic soda bottle which fits over the form after the bottom was removed. A heat gun causes the plastic to shrink to the shape of the plaster model.

Once formed, the threaded neck is split down the middle with a band saw. This will receive a piece of 1/2″ PVC pipe to be held in place by the neck and a pipe clamp. It’s possible to stop there, but a second video details an additional bottle used to make the device more rigid. See both videos after the break.

This manufacturing process is aimed at parts of the world that don’t have access to advanced prosthetics. We think it’s a wonderful demonstration of what can be done to improve the lives of amputees. We also think it’s a technique that can be used in other projects… we just haven’t figured out what those are as of yet.

It’s amazing how versatile this plastic waste can be if you put your mind to it.

[Thanks Chris]

Comments

  1. Zee says:

    I’m surprised by the massive load that bottle can handle.

    Also the second video is broken

  2. StevenD says:

    Nice construction technique to add to the repertoire. Thanks! Can be used for making sculptures, movie/play props, toys, … I guess smaller bottles can be used too and I wonder what other plastics. A ventilated area may be required as the heated plastics may give off fumes.

  3. Alex says:

    Impressive!

  4. Trav says:

    I’ve used this technique in a couple areas.

    I needed to keep 2 extension cord plugs locked together. I put a water bottle over them and heated them up, works like heavy duty heat shrink.

    The other was in a pinch situation. I was out doing lawn work and the top for the gas can split from being screwed on too tight and now leaked. I took the top off, and slid a water bottle over it (that I found blowing around the yard), held it up to the lawnmower exhaust, and it shrunk down. A little trimming and it has worked perfect for 2+ years.

    I stumbled on these by trying to re-use 2-liter bottles for vacuum forming plastic. It didn’t work. The blown plastic bottles shrink back to their relaxed state when heated and pull out of the frame.

  5. Noghiri says:

    I think it could be used to make low-cost molds, but I could be wrong.

  6. Charles P. Lamb says:

    An improvement comes to mind–how to remove the armature without cutting the bottle? A green sand armature is likely too soft. Perhaps a green sand armature with a coating of hardened salt would work?

  7. chango says:

    Now if only you could recycle PET into Makerbot filament…

  8. Hirudinea says:

    Couldn’t you just use the cap to attach light duty items, like a fork? I mean its not like they cost alot to make in total, so you could have a bunch for different uses.

    • jaded says:

      I’m certainly not an expert on prosthetics, but I suspect the addition of the PVC pipe puts the tool at a length similar to where the hand would normally hold it.

      Consider eating with a fork if your arm was severed midway between the elbow and the wrist. If the fork is at the tip of the arm, you’d first have to straighten your arm and then lean over the plate to stab the food, and then you’d have to flex your elbow to a very tight 60 degree angle and rotate your shoulder to raise your elbow to reach your mouth. With the extension holding the fork, you could keep your upper arm more naturally by your side, keeping the elbow flexing looser, and using less shoulder movements.

  9. WhiteCrane says:

    Looks like I found out a new way to encase my robot parts. I don’t know how well paint would stick to the plastic though, but clear robots are just as cool I guess.

  10. drake says:

    I swear I read this before

  11. Mike says:

    Nice. I’m going to try this soon.

  12. Drone says:

    This would be almost useless if 3D printing wasn’t so slow and expensive – a situation that does not appear to be improving, especially on the expense side.

  13. Brian Cribbs says:

    Kudos to not making the title “Amputee Hacking”. It’s surprising how much weight that simple form holds.

  14. arfink says:

    For a more suitable mandrel that would make it easier to get the bottle off after shrinking, have a look at their video about doing vacuum based sand casting. That would work very well.

  15. anonununun says:

    great videos! and the vacuum sand casting mentioned above is worth watching too

  16. Khanzerbero says:

    I used that technique once to fix a LNB whose package has been borken by a bird.

  17. pRtkL xLr8r says:

    So wait…could this be a cheap and easy way to make that Stormtrooper costume I always wanted???

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