This device was designed and built by myself based on relevant descriptions and several pictures of similar products. It was originally intended as a gift for a bass-playing friend. I had no idea about its specific working principle and just made some general speculations: it needs to resonate at a specific frequency, which in turn depends on the combination of weights and springs. Therefore, I paid special attention to adjustability in the design - just insert any length of metal wire through the reserved holes, put the appropriate weights into the box, and flexibly adjust the spacing between various components with the central threaded bolt.

Unfortunately, I never received any feedback on this device. If you've also tried making it yourself and successfully got it to work, feel free to share your experience with us anytime!