My problem was being able to fit the coroplast in my car... as it was, I just barely fit a piece big enough for a 2 x 3. It's going to be a 2 x 3 stacked on top of a 2 x 3 by the time I get done, though. Right now I only have the one guy, and he seems perfectly happy.. and I think it'll be plenty big enough for two once I have it completed. The cage he was in before, that I thought was HUGE, turned out to only be about the size of a little bigger than 1 panel, by about 3.5 panels. His hidey house fits nicely in the middle of his cage, and once I have the hay rack on the second story he'll be able to run without having to go around it.
All told, when I put his first (pre 'gutted-dresser' cage) cage on top of the C&C cage, I see that it's well under half the size. The thought that I used to have two in there makes me feel like a rotten piggy-mom.
... hrm.. and I actually just got an idea for using that old cage as a third story..
And I LOVE the little 'putt-putt' thing. Mine puts a little butt-shake into it as he's going along, and sometimes goes completely nuts, like when he hears the 'veggie-bag' being opened, and the putt-putt turns into a squeaky run around and 'popcorn'. It's so cute!