@Mossy I used to use US pennies back in the day outdoors it worked but was a pain. I did find if you take a bottle of beer leave about 3 sips in it and push it into the ground so the opening is flush with the soil the snails and slugs go into the bottle and get stuck. They cant resist the yeast in the beer. Some days I would have twenty or more in there. Kept them off the plants though.