Changeable Light-Up Cap and Headband

Learn about simple circuits and make your own changeable light up cap. This project uses sewable LEDs and conductive thread to make a cap or headband that lights up when the buttons are snapped together. The sewable components are wearable e-textiles, they have large sew tabs to allow them to be sewn into fabric.

Safety Warning:


  • Swallowing may lead to serious injury in as little as 2 hours or death, due to chemical burns and potential perforation of the oesophagus.
  • If you suspect your child has swallowed or inserted a button battery immediately call the 24-hour Poisons InformationCentre on 13 11 26 (Australia) for fast, expert advice.
  • Make sure the battery is correctly secured.
  • Dispose of used button batteries immediately and safely. Flat batteries can still be dangerous.

What You Need:

  • Sewable LEDs

  • 1¬†Sewable Coin Cell Battery Holder

  • Conductive Thread

  • 2 Pairs Sew on Snap buttons

  • 1 Lithium Battery 3v CR2032

  • Coloured Felt

  • Coloured Thread

  • Sewing Needle

  • Hot Glue Gun (optional)

  • Cap or Headband

What You Do:

Battery Patch

  1. Cut a small rectangular piece of felt the same colour as your cap or headband.

  2. Place the battery holder in the centre of the felt (You can add a small drop of glue to the back to secure it in place).

  3. Place the female button snaps on ends of the felt on the reverse side to the battery holder (You can sew the snap in place using regular thread but be sure to leave the side closest to the battery holder free for your conductive thread).

  4. Using conductive thread sew from one of the positive terminals on the battery holder to one of the button snaps. It is important to get a good connection to the battery terminal and the snap 2-3 loops of thread will hold well.

  5. Using a new piece of conductive thread sew from one of the negative terminals on the battery holder to the other button snap. Be careful not to cross the paths of the negative and positive threads as this will create a short circuit.

  6. Cut a piece of felt the same size as the battery patch and cut holes for the snaps. Stick it on top of the battery patch to cover the thread. This is used to insulate the conductive thread.

  7. Sew your Battery Patch onto your cap or headband. You might like to leave the top of the felt un-sewed so you can change out the battery or turn off the switch.

Light-Up Patch

  1. Cut out the shape for the base of your light up patch.

  2. Place the male snaps onto the patch equidistant to the snaps on the Battery Patch. You might like to sew these in place using regular thread but be sure to leave one side free for the conductive thread.

  3. Sew your LED to the snaps using conductive thread (The negative side of the LED needs to connect to the snap which connects to the negative side of the battery patch and the positive side of the LED needs to connect to the positive side of the battery patch to make a full circuit. You need to sew 2 or 3 loops into each LED to ensure there is a good electrical contact with the thread.

  4. If your patch has more than one LED they need to be connected in parallel i.e. It should look like a ladder with all the positives connected in one line and all the negatives connected in one line.

Test that your circuit works by connecting the snaps of the light-up patch and battery patch. The lights should light up when the snaps are connected. If they don't light up make sure you have not mixed up any positive and negative terminals and make sure there are no crossed threads. You can make multiple light up patches and change the design of your cap or headband.

How It Works:

The thread is made from stainless steel which allows it to conduct electricity, the metal button snaps are also conductive so when the patch is snapped in place the circuit is completed and the lights light up. The lights are sewn on in a parallel circuit as the resistance of the LED is too great (the lights wont light up) if you try and connect them in series.

What Next?

You can make a variety of different light up patches to connect to your cap or headband just make sure the button snaps are the same distance apart!