The easiest way to make a bug is to find a sound transmitter, usually found in micro phones, the size depends on your purpose, next you would want to connect it to a transmitter, preferably one from a walkie talkie, because they are the easiest to manipulate. Then you want to connect the wires with a soldering iron or gun. After that you need a battery usually the ones that are the size of a pennie. From there you need to rig it so it has a wire connecting to the positive terminal and one to the negative. After this you would need to spice the positive wire and connect it to the positive terminal on the sound transmitter. Now take the second part of the splice that isn't connect to anything and connect it to the transmitter. You need to do the same thing with the negative wire splice it and connect it to both negative terminals on the sound transmitter and transmitter.