2x4x3 would work nicely. Our current setup is 2x4x2 but separated. Do they need more head room on the bottom level though? That is what concerns me most about our setup now. They only have one small corner to raise up in and it just feels like they need more head space as opposed to more to play on.
Honestly, we thought we were doing right by ours when we built this. It was larger than we had seen other rabbits in and several people we know with rabbits said we were spoiling them by giving them so much space. I laugh now because it isn't that much space at all.
Thankfully we DID give them a few hours a day to run.
Here is how our cage is set up now. (ignore all the text on the photo, I was showing a friend who was interested in making a NIC cage, she went with a smaller pet store cage in the end) It was originally designed for the parents of the buns we have now. The parents were re-homed (together) and my girls prefer to stay in the same cage so they are both trying to fit themselves in to half of this. It doesn't works so well but they get mad when separated. It's only been a couple of days and we've made sure to give them lots more time out of the cage so it has worked but I am ready to remodel. My new NIC panels will be here on Thursday. As much as I'd love to tear their cage apart today and start remodeling, I will wait until the new box gets here so I have more to work with. We have extra panels from the original 2 boxes that we used for this but they are in the garage holding balls and gloves and other outdoor toys and the shelves I made with the leftovers fit the space so well that I can't justify tearing them apart for cages.
I will definitely be adding a 3rd story. I'd like to keep the 2x4 arrangement because it fits nicely in the space we have. As you can see, anything deeper would be in the way of opening the door next to the cage. Anything longer would mean a new rug (though we've had two new rugs since this picture was taken, I just bought a new one over the weekend! and would like to use it a bit) too... not the end of the world, but I like how this size fits the space.
We ARE switching to pellet litter over the pine shavings (that we had no idea until a few days ago were bad for them
) and I would like to get a dish of some sort for water rather than rely on the water bottles. Thumper, in particular (though he won't be in THIS cage, yet) prefers to drink from a dish. The panels behind the cage were to prevent spray from going on to our walls. Our male adopted the bad habit of spraying. Of course, who can blame him when he was housed right next to the female? Live and learn, I suppose and we are definitely learning more about proper care now that I found this forum. I did hours of research before but never found such great information all in one place. I was led to believe that we had a great setup here...
I want to go one higher at least. We had to put a top on the cage with these guys because Rascal is a jumper. She managed to jump clean over a tall baby gate. We were on vacation and my brother was coming in to feed her and clean her area (before we had Bitsy) and every day he kept finding her out roaming the living room. We couldn't believe it until we caught her jumping clean over. She was quite proud of herself. LOL Anyway, I would love to leave some open area at the top when we remodel so that the cats can visit. The cats adore the rabbits and the rabbits love the cats and right now 2 of my cats spend half their day in Thumper's enclosure. We find them cuddled up asleep with him all the time. <3 I was thinking more head room on the lower level, maybe an L shaped shelf in one corner that they can lounge on or use to move to the 3rd level... I might even go one more wide (5 instead of 4) but as I mentioned that means replacing the rug we use for flooring. I also want to try the dowel method with the shelves instead of using the NIC panels for shelves like we've done. We did use the small gauge wire mesh that I can't even put my pinky through and I know it doesn't hurt them but carpet seems so much nicer, especially since they are all litter trained really well.