[veloxo]

For some use cases, copper-foil adhesive tape can be bought relatively cheaply.

I've applied it to some frequently-wet surfaces to successfully prevent microbial growth that previously had to be sanitized on a regular basis.

The adhesive keeps keeps it watertight to the surface, but the stuff I got could also be peeled off without residue. Because it's copper, it does develop a patina and leach green copper oxide onto towels when wiped. Brass tape may be a less-corrosive alternative.

People also use it for EM shielding, eg around electric guitar pickups.