You can have a dust bath indoors too, if you have a spot in the coop that is suitable. This one is a simple pine box under a platform, I chose this spot to keep the sand contained as much as possible. It's about 30"x18"x7". I'd make it 12" high if doing it again. With one indoors they will dust themselves frequently. I used play sand and about 4 cups of food-grade diatomaceous earth.
You may be surprised how your hens manage to dig in stony ground, though! And it keeps their nails filed.
You may be surprised how your hens manage to dig in stony ground, though! And it keeps their nails filed.