I currently have my 7 week old girls in this while I wait for them to get big enough to go in with the big girls.

BestPet Chicken Coop Chicken Cage... https://www.amazon.com/dp/B00OVUBOAK?ref=ppx_pop_mob_ap_share

But to be clear, I'm in a pretty urban setting with a solid wood fence and 3 dogs that keep most predators at bay. You may need to add some hardware cloth and really secure down. I also added an outdoor dog house to the opening at the end so they have an enclosed space to sleep in.