How It Works

Plastic Bottle Prosthetics
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1) A cable is attached to the tip of the tentacle, along the user’s forearm and shoulder, and secured to a harness on the user’s back. With no cable tension, the default position of the tentacle is open.


2) Extending the arm or flexing the shoulder pulls the cable, causing the tentacle to curl.


3) Once the user retracts the arm and/or shoulder, cable tension is released and the tentacle returns to the default open position.


The tentacle is made from an 8″ piece of garden hose with linear notches cut out with a bandsaw. A bike chain fixed at the tip and running down the inside of the hose both actuates the tentacle and restricts movement to along one plane. Without it, the tentacle would flop to one side when the cable is pulled.


The end of the bike chain is attached to a bike brake cable inside a piece of PVC pipe. When the cable is pulled, the bike chain curls since it is fixed to the tip of the hose. A water bottle serves as the socket to attach the prosthetic to the amputated upper arm. The bottle can be custom molded to the user using a heat gun, propane torch, or open flame. Hose clamps and duct tape hold the hose, PVC pipe, and bottle together.


Part List:

  • Garden hose
  • Bike chain
  • PVC pipe
  • Hose clamps
  • Water bottle
  • Brake cable
  • Brake cable housing
  • Vinyl arm band
  • Velcro
  • Nylon strap
  • Duct tape