If you’re looking for a last-minute Christmas present, you probably won’t have enough time to reproduce [Helmar's] candle-powered Christmas card. He’s been working on it for a few years now, since his first prototype in 2010. Though he pieced together the original card with parts lying around his workshop, the most recent iteration looks like it belongs on the shelf in a store.
We last saw [Helmar's] work two years ago, when he shared his Full Color Laser TV. This project is a bit more compact: the circuitry was printed with conductive ink on the cardstock, and all the required components are held together by conductive adhesive. To power the electronics, he decided against a battery and instead chose to embed a solar cell on the inside of the card. Placing a lit candle inside the open card provides enough juice for the exterior of the card to shine.
You can see a video of both the current and prototype versions of [Helmar's] cards after the break.