Passive Amplifier

Simple and easy to do using an empty ambient deodorant,increases the sound more than 20 decibels without battery nor wires

A deodorant tin can can,not the aluminum one,and to cover it some kind of adhesive sheet,like this ( carbon fiber),or simply paint it

Take off the upper part part of the can,with the help of a plier or screwdriver

With a handsaw or a angle grinder Cut both sides of the can,the upper one will be the base and the lower one will be a sound reflector

Bend a little bit the bottom side,in order to let us introduce in the can,and with the help of a hammer bend the upper side as seen on picture,this will make a better seat of the can on the base
Also we have to mark a rectangule according to the size of our cell to let us put it in,make the little window some mm bigger so the cell enters freely

And after soldering the base and the sound reflector in the inside,I covered It with fiber carbon sheet ,It is a really efficient amplifier,It amplifies enought the sound of the cell