I had just built a custom cage about 2 days ago that is close to what you were talking about.The entire cage dimensions were 48" x 24" x 75.5". Although we messed up with the building, and drawing process the cage still looks really good. For the inside of the cages there are two 48" x 24" x 20"
and one 48" x 24" x 25" cage. Also in between each cage is a 4" empty space that is used to place the light fixture cords, and ect... in. I will post pics as soon as i take some (so as soon as the cage is done). I will also post the prices if you wantr them...