My blue lefty Luke has some crackling when plugged in to an amp so I'm going to shield the cavities in the hope the crackle goes away. I'll admit my knowledge in this area is a little sketchy but this little venture should fix that PDQ.
I started with some youtubing my new word :-) some time ago and brought some self adhesive copper tape. I know you can use aluminium tape that you can get from a hardware store but decided to spend the five bucks on the real thing.https://www.youtube.com/results?search_query=shielding+a+guitar
An example of someone shielding a guitar from the search I did above.