Thanks go to conanh for his super cool, "pea-less" 2-tone design!! I made a couple of his originals (and they are great!) but I noticed that they didn't seem to have two distinctly different tones. I watched a few youtubes of whistle builders who made their whistles out of wood, and they demonstrated that, by increasing the size of the output hole, the tone is changed. (To be fair, they also increased the volume of the chamber- it appears there are a lot of variables!) I changed conanh's design by making both chambers the same size, then making chamber 1's output hole smaller, and moving the wedge forward to fit the new smaller hole. The finished product doesn't have a huge difference between tones, but it is different, and when you hear both together, it is a nice, distinctive sound. Oh- and this thing is LOUD!I printed this with .2mm layer height, 50% infill, 2 vertical shells, 3top/3bottom horizontal shells, and it works great! When I tried printing one with layer height of .3, it didn't work as well (my guess is print quality has to be higher for an air-tight whistle)