if you want to fly them then a cheap chain link dog run with deer netting should suffice for during the day, for now, then just move them back/lock them into more secure loft coop or cage at night. i for a while just had my porch and balcony thumb nailed with tarping and deer netting (its decently small gauged tuff thicker black plastic), with rabbit cages and dog crates/houses stacked. there is also plastic poultry netting which should be BOP resistant enough for day use, but youd need something smaller gauged and metal so rodents and other problem animals couldnt get or just reach in even, if were going to leave out at night, and maybe as ill be doing when get better place set up agasin mosquito netting, even though never had problems for some reason with them with pigeons, like did with doves and some chickens at night (though you can leave a low watt buld on out by them so they can see to eat them). attaching a closable six sided plywood loft, would work to keep most thing out at night then just open up after gets bright out, to let them get into open air flight pen.
Pics please, as these are two of my classic favorites.
