I bought mine a treat ball from Tractor Supply. Its about the size of an orange and pulls apart to fill with treats. Both my chickens & ducks love it. They learned how to use it soon as I showed them. Cost about $5.
That's simple....change your setup to get them out of the coop! I've never seen a bored chicken out on pasture, as they are too busy being chickens as they were intended to be. It really doesn't take much to put chickens out on healthy soils and grass, just a little time and a little extra money~initially~and then the system pays for itself for years.