Rocky is in extreme nesting mode, and we've been indulging him. As always, I feel compelled to write that whether or not to allow your bird to play with boxes depends on that bird's individual personality. I would not allow any of my females to play in boxes as I do not want to encourage egg production. I would not allow my male birds to play in boxes if it exacerbated any of their hormonal behaviors in a negative way.That being said, Rocky has been going through a box every 1-2 days. When I got home from work yesterday, he'd turned the box into a little cave, and would hang out in there with his fabric, wood to chip, and his eggs (plastic balls.) This box was entirely shredded when I got home from work today, so he'll get a new one tomorrow.
He is quite adorable in his nest. He sings little songs to his "eggs," gently moving them around, making sure they're comfortable, etc. Shoe boxes and beer kit boxes appear to be the right size. Good thing we have quite a few of both at our house!