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]

21 thoughts on “Learn A New Fabrication Technique From DIY Prosthetics Builders

    1. The R/C guys have been shrinking plastic soda bottles over their custom battery packs for years. While searching for a link, I found this interesting off-topic link:

      Hmm… Phil Torrone busted by the TSA? Haven’t we heard that name around here before? ;-)

      Anyway, back on topic (almost)… They ought to call this one the “TSA Special”:

  1. 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.

  2. 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.

  3. 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?

    1. 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.

  4. 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.

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