Whistle papercraft - how to build.

A papercraft whistle, is it possible?
This is the question which gets me trying.
I have made a lot of prototype and a lots of trial and error.

After all those prototype, finally I come out with this final design.
I am sure it's not the best but it works every time I build with this template.
I make three version of it, a short one, medium length and long one.
Please watch below build video for details:

Thanks for watching :-)

The template of the whistle can be downloaded here:

PaperWhistle_template.