(Copper bands and copper tape)
Slugs and snails do not particularly like copper but they will cross if they want to. Just see our video
or do the experiment yourself. Fix tape around the inside
of a pot, put some snails in it and leave overnight (when they are most active). See how many are left in the morning.
However, copper oxidises and becomes even less effective.
This explains why people find that copper does not really work.
Furthermore copper in large amounts is toxic
(which is why it is used in fungicides) and tape leaves a nasty sticky mess on your pots at the end of every year.