My students and I have been studying electricity, and these cards really made the connection between learning about open and closed circuits and applying the knowledge to something fun and useful. The kids were super creative, and their faces lit up when their cards did! Even though we did this for Christmas, it could be done for any occasion. Here are a couple the kids came up with and an example of one of the circuits on a single-bulb card.
Here is the tutorial I used to get started. Copper Conductive Tape, LED lights, and button batteries (CR2032) were the main components.