Hmm... it may sound like you have a bad connection somewhere... or the pot needs to be replaced. If your guitar is old (8 years or older) or it's a guitar that uses lesser quality production methods... you may just have a bad connection somewhere. If you are familiar with a multimeter you can use that to check all the connections to the pots, to the jack, to the switch, etc... If not, the "buzz" may be coming from the single coils... AKA 60-cycle hum. Some people react differently to the old single coils... I was raised on single coils so I'm use to the hum, most people aren't.... and it bothers them. This can be counteracted by playing your guitar in the 2 or 3 switch positions... your guitar should have a reverse polarity middle pickup... that will cancel out some of the hum when you use it in combination with either the neck or the bridge pickup. Also... about shielding... copper is the best material to shield with.... the silver foil that you are talking about doesn't really do that much at all. You get information about shielding at stew-mac.com. They should have the potentiometers and shielding you will need. They also have some handy information on all that stuff. If that stuff doesn't help you out with diagnosing your problem... sorry. haha. good luck bro