Handy Engineering

Public summary: 

Build a model of the inner workings of your hand! Learn about how muscles and tendons work together to control the movements of our fingers, and have a model to take home, made of simple household objects!

Build a small working model hand from card and straws!
Useful information
Kit List: 

Drinking straws
A4 card
Printout attached below

Packing Away: 

The hand packs together with the lung model and handy engineering for storage. The box is in three pieces, first place hand down and fold at the hinges, using the hook and eye to secure at right angle. The fingers of hand should bend upwards however you may need to manually position hand to get this to fit. Then place the non-lung piece on the opposite side, tuck the strings through the provided gap and fasten the two small carabiners. The hinged triangle can hold tuperware and the slot can hold the folder for handy engineering. Then place lung on top, ensuring it locks downwards. Fasten the large carabiners on top. Carrying the box using the handles on the bottom, either with two people also using a hand to prevent tilt or one bear hugging.


1. Cut out around the hand.
2. Collect 5 pre-cut straws.
3. Tape down a piece of string over the end of each finger.
4. Thread a pre-cut straw onto each piece of string.
5. Using the sticky tape secure the straw between each of the joints.
6. Cut the straws a little way below the bottom of the fingers.
7. Cut another 5 short segments of straw and tape these by the wrist of your hand model.
8. Thread each piece of string through a separate straw.

You can also demo with a "How science works" theme if you have no clue about "how the hand" works. We study various models of how the hand works of various complexities. The paper model we make is simple but has more flaws than the more complicated Hand Model. You can get them to try and recreate motions on the two models and their
actual hand and look for muscles moving.

What does the model show?

This string running up each of the fingers represents muscles that originate in the forearm running up each of the fingers to insert in to the distal phalanges of each finger. The tape represent the ligament that attaches muscle to bone. The string will represent flexor digitorum profundus that flex the distal interchangeable joints and can also flex metacarpophalangeal joint. The straws represent tendons between phalanges that hold the muscle tendons parallel to the bone allowing it to act as a pulley. Damage to these tendons results in bow stringing of a the muscle and compromises extension of a finger.

Risk Assessment
Date risk assesment last checked: 
Sun, 26/01/2020
Risk assesment checked by: 
Date risk assesment double checked: 
Mon, 27/01/2020
Risk assesment double-checked by: 
Beatrix Huissoon
Risk Assessment: 

Small model of tendons in hand, using card, straws and string.

Hazard Risk Likelihood Severity Overall Mitigation Likelihood Severity Overall
Scissors Risk of cuts. 2 3 6 Younger children should be accompanied by an adult. CHaOS volunteers to oversee carefully
Ensure kids are behaving sensibly at all times.
Use safety scissors.
Call a first aider in the event of injury.
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