Whether you're trying to quiet the hum on your old single coil Strat or Telecaster, or create a DIY wireless charging station for your phone, the copper tape sold to repel pests from the garden is an inexpensive and easy-to-manipulate material for the job.
By the way, slugs actually do HATE copper tape, evidenced by a 2004 paper ("Behavioural response of slugs and snails to novel molluscicides, irritants and repellents") in which scientists placed snails and slugs in little time trails. Citing a slowed pace of .5 centimeters per minute, they concluded that the "copper significantly reduced the velocity of snails."
Apparently the whole copper-slug thing is an urgent question to some people. I admire this guy's testing setup: