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Give those flesh and bone fingers a rest and try out a brand new plastic one! This is a way not only to creep out yourself, but also get an introduction to a thing or two about anatomy. You can make just one finger or an entire hand!

The details:

  • What: A straw finger!
  • Time: ~ 5 minutes
  • Cost: ~ 3 cents
  • Materials: Tape, Straw (large), Zip-Tie
  • Tools: Scissors
  • Concepts: Muscles, Tendons, Tension, Force, Anatomy

Step 1: Measure and Cut Zip-tie

Feed your zip-tie through your straw so that it sticks out a little bit on either side. It works well to use the fastener end as a handle to pull with, so cut the other end if it feels too long. Take the zip-tie back out for the next step.

Step 2: Cut Holes for Joints

Time to make the joints of the finger. Fold the straw and cut a triangular slice out. When you unfold it, you fill you've made a diamond-shaped hole.

You'll want to do it again a bit farther down the straw such that the holes are lined up on the same side of the straw. This is where the straw finger will bend.

Step 3: Attach Zip-tie

After you have your joints, time to affix your tendon to the end. Feed the zip-tie back through and fold it over the end of the straw to tape it. You'll want to tape the zip tie on the side of the straw where your holes are for easy bending.

Step 4: Make That Finger Wiggle!

You'll want to bend the finger a bit at the joints to crease them a little bit for easy bending. Then wiggle away! Feel free to cut more joint holes to make a crazy alien finger. Or cut them on different sides to see it warp in truly strange ways.

In this model, the straw is modeling bone (though connected, sure), the zip-tie as a tendon, and the force of your hand pulling as a muscle. You can have students compare their own finger movement, and see if they can trace their tendons up their hand.

A brief educational page on tendons and hands can be found here!

<p>:) :) :) If you want to take this a bit further, I stumbled on this tutorial about a month ago for something most similiar: https://www.stanwinstonschool.com/tutorials/make-a-cable-controlled-mechanical-hand</p>
<p>That is indeed the great extreme version, and neatly the same mechanic used a bunch of the low-cost 3D-printed prosthetics coming out. Thank you for sharing! </p>
<p>I am teaching an innovation club and I had the students make this. They loved it. Once girl went so far as to attach several to a cookie container she has to make a robotic hand. Thank you!</p>
<p>AIP3! This is such great news, and we couldn't be more excited about you using it for your innovation club! Keep checking in for more Instructables, as these are really targeted for educators like you! Where in the world is your innovation club?</p>
Run a string just a bit longer than the straw through the inside. Attach to top snd let excess string hang from the bottom. Pull on the string to flex your finger.
<p>Great idea! Indeed, you can do it with just a string. Thank you for writing! </p>

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Bio: The Oakland Toy Lab is a community-based wonder lab for students to build, tinker, explore, make, break, and learn! We are writing up engaging science ... More »
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