This instructable shows you how to build your own bug zapper using recycled parts and is general in its suggestions. To see how I built my bug zapper, you can visit my website's bugzapper page here
Now having said that, there are countless of ways to build a bug zapper. It all depends on the types of bugs you're targeting and the size of the bug zapper you want to build. Also the design plays a huge part in the effectiveness of the bug zapper.
Update! For more info about how bug zappers work, you can refer to this linkDisclaimer
I am not liable if your shock yourself or injury yourself, working with high voltages is very dangerous!!