Those are "cubes" that we modified. I got the idea several years ago when I made a rabbit cage out of them. Here's a website that gives a lot more information about how to use them. They are great! We've built guinea pig cages, rabbit cages, rat cages, and now duck brooders using them.
http://www.guineapigcages.com/cubes.htm
Oooh - that's so cool! Thanks! 
The first of 11 kids in the bestest family in the world!
The Dogs: Tipper (black Lab/Cocker) and Boaz (yellow Labrador Retriever)
The Cats: Trixxie (tortoiseshell) and Pumpkin (snow shoe)
The Ducks: Anconas in black, chocolate, and lavender: Mr. Darcy, Mr. Bingley, Lizzy, Jane
"I can do all things through Him Who strengthens me." ~ Phil. 4:13
The first of 11 kids in the bestest family in the world!
The Dogs: Tipper (black Lab/Cocker) and Boaz (yellow Labrador Retriever)
The Cats: Trixxie (tortoiseshell) and Pumpkin (snow shoe)
The Ducks: Anconas in black, chocolate, and lavender: Mr. Darcy, Mr. Bingley, Lizzy, Jane
"I can do all things through Him Who strengthens me." ~ Phil. 4:13
