I was giving a subscription to MAKE this year to a friend for Christmas, so I printed out one of the print-at-home gift cards to announce it. Here’s my Flickr set showing how you can add LEDs to a card using conductive thread and a watch battery with holder. It’s pretty easy and uses the same circuit as my electronic embroidery tutorial. The LEDs are wired in parallel with each other and the battery is on the back of the card. The threads run between the two folded layers of paper so as to be held secure.