Monster Hunter: World | How to get Flashfly Cage Gadget

It's available when you have to hunt down the Kulu-Ya-Ku. [2nd Quest]
Once you kill the birb go after your new gadget, it's that simple.
The only annoying part is get that swing on the first time.
It's a gadget that stuns monsters with a flash of light. They can use this more often as their proficiency increases.