This is a air siren making 96dB noise. It use a 2 brushless motors and Arduino Pro Mini as a controller.
We don't think, that full instructions are really neccesary, because there is no need to build a copy. BUT! You can take our model, and create a new project from it with some modifications: your own motors or another controller, etc.
Some recomendations: for more noise don't try to spin it faster: you just make a higher pitch of sound. You must to make it BIGGER! At various RPM (more or less) it's generate same level of dB.
Two different rotors with different number of blades create this signature sound of AIR SIREN, so don't use only one. But, if you want just a loud thing, you can use one.
Use powerfull motors: rotors are very resistant at high RPM.
Oh, and use it carefully: sound is really scary to random people on streets, we know it on our expirience
Rotors are required a good balancing and flatness
Materials in our case:
T-motor MT2212 750Kv (from old quadcopter)
ESC DJI OPTO 18A
Arduino Pro Mini
DC-DC converter 16 to 5V
Some M3 nuts and bolts
Usual case of Arduino-controlled ESC . We used a DJI ESC - it's can't provide a 5V for Arduino, so we used a DC-DC converter. Usualy atnother ESC can deliver 5V without converter
Instead of instructions, you can see the photos, they pretty self exlanatory
At this page you can find all info about ESC contol with Arduino https://howtomechatronics.com/tutorials/arduino/arduino-brushless-motor-control-tutorial-esc-bldc/