Believe me, I've tried most things short of poison.... egg shell, sharp sand, coffee grounds, copper tape, copper impregnated material, sheep's wool, plastic funnelly things (OK to keep slugs away... no good against snails)
But... sooner or later my vegetable plot is rent by a high pitched wail, my own, as I find the latest glistening stump of what was once a healthy squash, courgette, bean plant, whatever.
I have been thinking of growing some vegetables in pots anyway. So, following The Old Man's Battle Plan... I have purchased a large... very large... drip-tray and some clay pot feet. Then I's put the tray out in the yard; put the pot feet in the tray; put pots on the pot feet; planted beans in the pots.... and filled the drip-tray with water. Voila! A moated bean-growing system.
Maybe the little gastropods will parachute in? I cannot put that past them.... and I will let you know.