When I was younger I used to want to eat everything.And my parents didn't know what to do.So they decided to watch to see what things I wanted to chew on the most.Once they figured out what things,after i had gont to bed the put hot sauce on the things i chewed on.Now if you put it on something and rub it in real well u cant see it.

Another thing that i have heard people do, and this seems to work,each time the chew on something they are not supposed to,take away a favorite toy from them.After a while they should realize what is going on and they will gradually stop.I hope this helps!!