I had an idea about snail trap. I was wondering if placing a plastic ring in a form of a brush around a pot with needles pointing down would serve the purpose. Using very tiny spaced needles (i.e. low density per cm2) would force the hungry snail to fall down due to a small contact area, right? (See picture).
If you made it out of copper, it would work even better, but that will be more expensive. Snails do not like to touch copper.
A chemical reaction happens when they crawl over the metal, which causes unpleasant feelings on their skin.
Al-tough not everyone will agree with me about this and I have seen snails just crawling over the copper, but most of them really hate it.