This is based on a reconstruction of a 36,000 year old bone flute found at the Divje babe I cave site in Slovenia. This 3D-printable version was created based on the work of archeologist Ivan Turk. The figures used to trace the flute's shape are from Chapter 15 of "Origins of Music" (©2000 MIT Press).
I tried to copy the shape of the flute as closely as possible, and ended up with a flute that is pretty difficult for me to play, though I'm not a professional player. I have at times managed to play several notes with it. (You can find videos of the reconstruction made by Ivan Turk et. al. being played by a professional player.) It's basically an edge-blown flute with a diatonic scale, with the opening covered for some notes.
Please iterate on the design or comment on how this flute can be made more accurate and/or easier to play.
Flute image and figure source:
Kunej, D., & Turk, I. (2000). New Perspectives on the Beginnings of Music: Archeological and Musicological Analysis of a Middle Paleolithic Bone "Flute" In N. Walin, B. Merker, & S. Brown (Eds.), The Origins of Music (pp. 235-268). Cambridge: The MIT Press.