Building a crystal radio isn’t exactly rocket science. Some people who build them go for pushing them technically as far as they can go. Others, like [Billy Cheung], go for style points. The modular radio and phone speaker looks like it came out of the movie Brazil. The metallic gramophone-like speaker horn adds to the appeal and mechanically amplifies the sound, too.
The video (see below) isn’t exactly a how-to, but if you watch to the end there is enough information that you could probably reproduce something at least similar. There are actually several horns. One is made from copper, another from paper, and one from a plastic bottle.
There’s also a socket to take different detectors. The radio appears to have a great frequency range, although you’ll have to squint at the video to see the schematic. We are hoping [Billy] will have it posted on his blog, too, eventually. Same goes for the templates for cutting out and assembling the horns. However, if you freeze the video, you can see most, if not all, of the major components.