How is it done? to get the best results a tripod is needed. The exposure should be around 10-30 sec. or longer if needed. Stay in front of the camera and do your writing with the different light sources. To not overexpose, the camera should be set to about iso100, and the aperture closed as much as possible. If there is still too much light, a nd-filter (neutral density) might be needed. And a useful tip: it is always nice to integrate the surroundings into the picture.
The toolkit consists of a collection of flashlights, biking-lights, flashing LED lights, fireworks & torches and even more sophisticated equipment. (Fireworks?! Oh now we're talking. Roman candles? The little tanks that shoot out sparks? Razzle dazzle snazzle. I like it.)
Leave it up to the Europeans and the Norwegian to pull these stunts.
Some of the best work I've seen lately has either come from Germany, France, Scotland or Norway. A trend is coming...