My newest fascination... the Hang. A musical instrument in the idiophone class created by Felix Rohner and Sabina Schärer (PANArt Hangbau AG) in Bern, Switzerland. It is made from two deep drawn, nitrided steel sheets that are attached together creating the recognizable 'UFO shape'. There is nothing inside the Hang but air. The top ("Ding") side has a center 'note' hammered into it with seven or eight 'tone fields' hammered around it. The bottom ("Gu") is a simpler surface that has a rolled hole in the center with a tuned note that can be created when the rim is struck.
Here is a video of Hang Massive duo Danny Cudd and Markus Johansson playing the Hang. http://hangmusic.org/music
Source: Wikipedia and YouTube