This is a single tone flute as made and used by pygmies (N'dehou). I saw this video and wanted to try the technique myself. As I didn't have any pygmy flutes laying around I created this model.

To use it hold the flut with the cut off under your lower lip, keep the flute vertical and blow though your lips as if your trying to blow at a fly sitting just above ur chin. Good luck! 

Update: I added profiles for all notes in 5th 6th octave, if you like to experiment. I also added a version with 4th octave included for H2-model printers as they are up to 329mm length.