First of all, I love the idea, but these cages always seemed better suited for people rather than the birds.
First of all, I HATE HATE HATE plexi as a cage material. It's hot, it does not allow air flow, they cannot climb on it, and it gets really dirty really fast, and has to be cleaned often... like every time the bird eats or poops...
Second, wood, as a building material for a large macaw... that cage is going to double as a chew toy.
Third, wood, as a building material for a large macaw... is a lot tougher to clean poop and dried food off of than conventional bird cages...
And a macaw is going to want to walk around on top of his cage. Which in this case, doubles as a chew toy...
So, those cages may look nice at first, with no bird in them, but they are also potentially very problematic...
You can get a good pervue hendrix enourmous double macaw cage on ebay for $650.00 and it will hold up for decades... which when you factor it in over the years is pretty cheap.
A DIY wood cage will probably cost you somewhere around $400 or more for the materials, and your bird might just chew it up in six months. DO IT AGAIN!
SO, I WOULDN'T.
Playstands and toys, yes. Home made is just as good, if not better.
Cages?! Not so much with a big mac.
A decent USED cage is usually a good way to go. Years ago a breeder friend of mine was upgrading her double macaw cages to stainless, and I got a $1000 Kings double macaw cage, that has been in continuous use for six or seven years, and I only paid $400.00 for it. So that would probably be a hit and miss classifieds project...
Then it's a matter of finding one in decent condition, and cleaning it really, really good.
One other word of caution, and that is some of the welding materials can be, HEAVY METAL TOXIC!
Heavy metal poisoning causes "macaw wasting" type symptoms... JUST HORRIBLE TO SEE!
You think cages are expensive? Try lifesaving vet bills on for size, and hope to god it works...!!! SO NOT WORTH IT!!!
