A mate of mine was interested in buying one of these for some years ago. Apparently, the original maker is a guy in Switzerland. To buy one, you had to commission it from him and agree per contract that if you later decided to sell the instrument you would sell it back to him or through him to someone else. He developed his own alloys and everything and had no interest in licensing the idea to anyone else. This was back in the 90s - no doubt by now others have figured out how to do it.