When you walk around the streets of a Finnish town on Christmas Eve, there are candles everywhere. The entrance to almost every home is illuminated. Quite often the candles are put inside an ice lantern, which makes them a special delight to the eye. And as my friend Kimmo demonstrated recently, it is not very difficult to make them. The only thing you need is cold weather and a bucket. You fill the bucket with water and put it outside for long enough so that the water at the edges freezes over. The time it takes depends strongly on the temperatures, at -10°C about 20 hours should do the job. Then you flip the bucket around and cut a hole at the top. Through this hole the remaining water can be drained and the candle can go inside. Voilà. More concise instructions can be found here.