How about beer traps?

Hi Seasiders and welcome to GoY. As it stands your question does not make sense could you amplify please.

He wants a slug/snail killer that won't harm his grandchild.

Any of the propriety slug/snail killers are safe around humans as long as they don't try to eat the dead beasts. Even then, I would have thought that a slug that had died naturaly would have a serious impact on the grandchilds digestive system!

salt takes the moisture strate out of them and they die strate away thow i wouldnt think snails and slugs that like damp would be to close to grand children . very young children do have a habit of sticking things in there mouths but they have to be very young ie 2-3 years . i as a child was always messing about with nature including snails,worms etc . they wont hurt them as such and itsm a learning curve . i did see a new advert about snails and dogs eating them on the tv with a risk to it but im not undualy worried excuse my spelling lol .