This was before I had a 3D printer so iteration consisted of me changing the design, uploading it, and changing it again after getting feedback.
In the end I knew it worked when YouTube user Landru613 uploaded a video of the recorder in action.
The 3D printed recorder and it's variations are available on YouMagine.
https://www.youmagine.com/designs/recorder-music-instrument
https://www.youmagine.com/designs/empire-state-recorder-v2-instrument
https://www.youmagine.com/designs/tree-recorder