when i was trying to do it before, it was hand made, from a polypropylene pipe... it wasn't exactly the same, probably, as a properly made standard instrument, and it is possible that my device was wrong in a critical way, and i managed to get sounds out of it, it just was really hard to get it to make a sound at all, i mean, at all.

most likely it was just too wide in the centre or something...

i remember studying the acoustics of tubes in physics in highschool... it was just probably too wide and too hard for my lips to form the sufficiently narrow hole and the right angle... i experimented a bit with changing the shape of the inner and outer parts of the thing

as this guy in the video says, it took him days to just get it to make a sound every time

i kept trying for maybe nearly 2 weeks before i gave up and tried making a second one with a standard side-blown aperture, using a end-closed flute and researched the dimensions to drill the finger holes for it

i mastered playing this tune when i had that second one:

https://www.youtube.com/watch?v=WDCNlqMgnvo