If you have a 5.56/.223 rifle, just keep collecting that spent brass for reloading purposes and wait until you have 32 cases that are beyond safe reloading, getcherself an 11 1/2" length of 2x12 and go to town. Take one half of the finished pieces and put them through a parkerizing process. The other half just gets tumble-polished. Coating of polyurethane for everyone! Enjoy!
That is really cool. It would probably be pretty straight forward to make. I made whistles out of .223 casings and .22 shells a few years ago. There is an awesome Instructable on instructables.com