I was waiting to add my .02 worth. Most outside aviary are built with the GAW wire. I'd guess most of the parrots kept in captivity are kept in GAW cages. Yes there's an issue with zinc in the GAW wire. I kept many zons in GAW pens, put they don't chew on the wire !! Some of my birds have been in this type of "cage " for 30-40 yrs. The only metal toxicity issues i've had are with pet birds and poor toys. I wash my GAW wire with a vinegar solution and "age" in the sun/rain for a few months. I do use SS hareware/fasteners when ever possible. I use a 1x2 14ga GAW 4' wide and 100 ft rolls. This will not stop things like cats, possums, coons,snake or insects. But it's good at stopping large predators like dogs, hawks,People. I also use a screen outside of the wire mesh. It stops the bugs and snakes . It something is trying to get in you'll spot it when you see tears in the screen. I'd think outside your kitchen window is a great place, but be watchful. A cat or hawk could cause panic and injurys. I'd also keep a window open to hear if the alarm call goes up.Nothing will make you want to buy a shot gun , any faster, than seeing a hawk hanging on to the outside of your aviary , trying to eat your pet. My breeders are outside 24/7 and i now have a good ,well trained watch dog. Even the hawks keep their distance. I'm sure we'll talk more about an outside aviary. I'd give some thought about framing and pouring a "pad".
PS the perfect size mesh would be 1/2' x3' , they make it just for outside cages and aviaries. You can even get it in SS !! I'd love to be able to afford to use it!!