How many hundred of pounds of shells do you have?

In W Washington, I'm going to say no. Slugs are such an every day part of gardening here, it takes a combination of things to keep them under control (notice I did not say gone). You could try some egg shells around some susceptible things like hosta, but you really need one of the environmentally friendly (iron phosphate) baits too like Worry Free, Sluggo, even Ortho makes one called Ecosense that is safe for children, pets, wildlife. Beer traps are helpful.

Besides the baits, I go out at night armed with a flashlight and a pump spray of 1/3 household ammonia, 2/3 water and spritz slugs - won't harm foliage, won't harm you, and they are gone in a heartbeat.

One more tip, be persistent and stay on top of them well into Fall - Fall, because that's when most eggs are being laid. I'm baiting just about every month but January.

Sorry, they don't work. That's what slime is for -- to protect against sharp stuff.

Beyond that, do as the previous post suggests -- be persistent and you can limit their damage. But know that you won't be able to stop them. No one can.

Well I work in a bakery and we use at least a box of 15 dozen eggs a day. How well does coffee work? if you have tried it. I will probably do some beer traps (Hope the dog doesn't get to them first...) and will try the slug bait. How do normally apply? around the base of the plant or perimeter of the garden?

around the base of the plant or perimeter of the garden? - Both.

Coffee - does not work at all.