Festive Electronic Greeting Cards Using Conductive Paint

This instructable will show you how to make electronic greeting cards for any occasion of your choice. However my objective here is mostly to demonstrate how kids can have fun making cards but also learn about electronics at the same time.

I will be using a new product from a company called Bare Conductive that have recently released conductive paint that dries and forms circuits. The potential of this product is huge as you can use it on paper, card, clothing etc.

You can either create a card from scratch or print a design out on card and add the electronics after.

Suitable designs will need to incorporate flashing or still LEDs though you are not limited to this. Here are a few that I have thought of:

Lighthouse
Santa with flashing red hat
snowman with flashing nose
Chanukah/menorah candles

Materials and tools:
Scissors
blank card
3mm/5mm Flashing/still LEDs
Conductive paint
3v coin/button batteries and holders
Colouring pencils or other decorative materials

Step 1: Design/create Your Card

1. The first step for this is to make a greeting card using blank card or purchase one from a greeting card shop. I found the best cards are the ones your children design. So I have a couple of those.
   
   I did draw the xmas tree card myself. Don't comment on my art skills. That's why I work in I.T.

Step 2: Place LEDs

When you have complete your design you need to place the LEDs.

I've got 3 x 3mm LEDs that are 2v. You may be able to use more. The conductive paint has been tested up to 12v. This means however that you would need 4 x 3v coin/button batteries.

1. Push the tin terminals of the LEDs through the card and bend them flat. The long terminal of the LED is positive(+) and the shorter one is negative(-).
   
2. Position all the LEDs so that the positive terminals are turned towards a negative terminal from another LED.

Step 3: Create the Circuit

1. In this step I've labelled the inside of the card with the connections that need to be made (see photo).
   
2. Using the conductive paint pen, squeeze a thin line of paint to make the connections I've indicated in the image(see photo). You may want to leave this to dry for a little while.
   
3. Next glue the batteries in place with the paint. You have 3 choices.
   Positive side up(no holder) or positive side down(no holder) or use battery holders.
   
   If you chose positive side up(see image), there is a chance that you will paint across both battery terminals. So for first timers I would recommend positive side down.
   
4. Squeeze a line of conductive paint onto the card and place the flat side(+) of the battery face down leaving some paint visible. Squeeze a line of paint from here to the remaining free LED positive terminal. Leave to dry.
   
5. Finally you need to connect the negative terminal of the battery with the remaining free LED negative terminal. This is a little more tricky at the battery is not flush with the card but raised up.
   
   You need to create a wire. I used a broken off LED terminal and bent it so that is would arch from the card to the battery and glued in place a both ends with conductive paint.
   
   Alternatively you could create a sprung paper switch (see image or this instructable)

While the paint is wet you will not see the LEDs light up. As the paint starts to dry they will slowly start to glow. Only when the paint is fully dry after a few hours will the LEDs glow at full intensity.