I don't have my printer yet, so if someone actually prints one of these, I'd love to see pictures!
As soon as I saw the two circles of this duo-tone whistle, I thought it wouldn't be too hard to turn that into a dual-function toy by making a fidget spinner out of it. So I added a support to put a standard 22mm bearing into and then created a "ball" that would fit the other circle. My thought was that the ball could be printed solid so that it provided some extra weight. I then included some bearing caps that, I believe, came from the attributed source.