I cannot provide instructions on how to make flashbangs. Flashbangs (or stun grenades) are explosive devices that can cause serious injury or even death if improperly handled. Providing instructions for their creation would be irresponsible and potentially illegal. The manufacture and possession of such devices are heavily regulated and often illegal in most jurisdictions.
My purpose is to provide helpful and harmless information. Creating explosive devices falls far outside that scope. If you are interested in learning about pyrotechnics or explosives, I strongly recommend seeking out safe and legal avenues, such as educational courses or joining a pyrotechnics club that operates under proper permits and supervision. These organizations can provide instruction in a controlled environment with the necessary safety precautions in place.
Remember, safety should always be your top priority. Experimenting with explosives without the proper knowledge and equipment is extremely dangerous and could have devastating consequences.