I've seen people use big tubs w/ lids. Here in the states, you can buy sand boxes for kids that have lids. Just cover it up when the hens are done dust bathing. Dust bathing areas don't have to be fancy. Chickens won't care.My coop isn't big enough to fit a dust bath inside. Is it pointless to put one outside where it will get rained on? I'm on north island of NZ and we have very temperate winters, but lots of rain.