Make a HUG ball

HUG was a project commissioned by the City of Edinburgh Council for its Traveling Gallery exhibition Access All Areas in 2007. The concept was for the object to seem to return the affection of a human hug, through the use of soft switches, recorded sound, and vibration. The feedback of visitors to the exhibition was extremely positive – it seems like the very simple interaction has something powerfully affective at its heart (you can see a paper describing this, accepted for ISEA 2009, here).

More than this, HUG demonstrates how many design decisions there are to make in a reactive textile project. Each step below gives you instructions to create a HUG with LED output, but also asks you to consider the alternatives open to you as a designer. This image shows three different versions of the ball; the pink one was purchased from Marimekko, the purple one with fur was made for Access All Areas, and includes vibration feedback, and the patterned one is being developed for the Internet of Soft Things project with LED output. These are all about the size of a football.



For a 25cm diameter HUG you will need:

Strong cotton twill (for the outer shell)

Calico or similar (for the inner shell)

Spacer fabric or foam

Zippers: 1 x 28cm (11 inches) fine toothed and 1 x 80cm (31 inches) larger toothed

LEDs: 8 sewable surface mounted with resistor (such as Lilypad range)

Filling – polystyrene beads, memory foam, Kapok etc

Magnetic switch and magnet

3V coin cell battery and holder

Conductive yarn (3 or 4 ply is easier for hand sewing)

Needle, needle threader, embroidery scissors

Sewing machine

Dressmaker’s chalk

Fabric shears



  1. FORM


To create a ball, print off the pattern pieces here at A3 for actual size (or scale and follow the noted measurements) HUG_patternPieces

Use a strong cotton twill for the outer shell, and a calico for the inner shell.




Mark the pieces on your fabric with chalk, and using fabric shears, cut six pieces for the outer and inner shells, plus the circular bases. As a guide, the circle measures 15cm in diameter including the seam allowance on both sides, and the long panel measures 31cm down the centre, also including both seam allowances.

Design decisions:

Explore other ways of creating the same form. Look at existing examples in toys and furniture. Try slicing the pattern up in different ways.

Explore other three dimensional forms. A pillow is far simpler than a ball to embed electronics into, and does not suffer from structural problems as it is scaled up. Consider how changing the form will change the interaction of a body with it.



Following the pattern marked here (link to follow), stitch a parallel circuit with 8 LEDs on one of the panels. The parallel circuit is like a ladder, with the LEDs forming the horizontal rungs. The yarn does NOT travel across the back of the LED board. Make sure all the LEDs are oriented the same way round, for example, with all the + to the right. This piece is marked ‘G’ because my LEDs are green.


Design decisions:

Change the layout of the LEDs, and test your new circuit design with crocodile clips.

Think about the number of LEDs being used. How many can the circuit take before the current doesn’t flow? After completing the project, consider how you might create a HUG with LEDs on every face?


  1. INPUT

Cut a circle of the spacer fabric and using the cotton twill base pieces, capture the magnet in the centre by stitching through all the layers at regular intervals.



Make the inner ball: sew the zipper to two of the faces. Leaving a 1cm seam allowance, and sewing right sides together, complete the inner ball. Turn right side out and test the zipper.

Complete the circuit: following the layout shown below, stitch the battery holder and magnetic switch to the inner ball top face. Making sure you join the + of the battery holder with the + sides of the LEDs, stitch a connection. The switch can be either way round (it does not have polarity). Remember to start and finish the stitched conductive yarn on either side of the switch – do not continue sewing behind it.


Insert the battery (+ side up). Test the magnetic switch by bringing the magnet close to it – your LEDs should light up. If they don’t, see the troubleshooting tips below. Fill the inner ball.



Make up the outer ball: insert the zipper first, and continue with right sides together.

Insert the inner ball, making sure the magnet in the top face aligns with the switch on the inner ball. Test for the interaction needed to activate the switch. You may need to add a foam ring between the layers if the LEDs light up too easily.



Design decision:

The magnetic switch could be replaced with, for example, a soft switch, or a tilt switch. Consider how choosing a different switch would impact on the structure of the ball and the circuit.

Try different fillings and test the change in interaction needed to activate the switch as a result.




  • If your LEDs won’t light up at all, are intermittant, or if they stay on until the switch is activated, check for the following:
  • All LEDs should be the same way round – all the + to the same side.
  • Connect positive LED to positive battery holder electrode, and negative to negative.
  • Yarn should be stitched through component holes a few times to create a good electrical connection.
  • There should be no loose ends or stray fibres anywhere. Finish ends neatly and thoroughly.
  • There should be no conductive yarn stitched behind components, or the current will bypass them through the yarn.
  • Battery should be new, and the right way up (+ is marked on one face of the holder).
  • The switch should be between the battery and the LEDs.
  • If the LEDs seem dim, try them in a darker room!
  • Remember you can use crocodile clips and a multimeter to check individual parts of your circuit. Go back to the tutorial here (link to follow).

HUG was a project commissioned by the City of Edinburgh Council for its Traveling Gallery exhibition Access All Areas in […]