Hanging cages are mostly used for breeders. People who have an outdoor building set up, with good ventilation, safe from the elements. Most people have an earth floor for the waste to fall in. Some have concrete poured for walkways, or like me, use sturdy wooden pallens for a walkway. If I find a good strong pallet that has wide gaps in it (wide enough for a kid or even an adult to twist their ankle in) I get 1x4 pieces of wood and fill in the gaps. (Nailing the new pieces into the pallet.) These are cheap and effective for the breeder looknig to save money. I usually can get my pallets free, either by driving around and seeing some set out for the trash, or asking a retail store if I can take some. They usually have so many they are happy to be rid of them.
On to the cages. These are my plans for small to medium sized breeds (Holland/Fuzzy Lop, Dutch, Mini Lop.) Adjust accordingly if your rabbit is bigger (over 6-7lbs.) I try to make enough room in each of my cages to support nestboxes and imagine there is enough room for a large litter of babies. All of the cages do not have to be this way. To maximize room, you can make "breeder cages" which are slightly larger to support the additional inhabitants. Bucks, juniors and unbred does do not need as large of a cage, but the extra room is always nice for exersize and stretching. I am starting to do this now, half of my 20x20ft barn has breeder cages that are 24x24x16". The other half will have cages that are 18x18" or 20x20", I haven't decided yet.
Let's say we're building an 8ft long cage. This would allow 4 holes measuring 24x24. I would recommend to purchase wire no taller then 18 inches, for small breeds. The extra height is really useless unless you have really tall nestboxes (for bigger breeds, or arched body type breeds) or unless you're planning on putting in ramps for exersize. Most breeders don't put in these luxeries. However some will put it in a cage or two, and put a rabbit in who needs some exersize. Ramps are good to build up shoulder muscles, from the constant jumping up and down from it. Some rabbits however will never get the hang of ramps and will not use them. It just depends on the rabbit.
However some people never use the space ON TOP of their hanging cages. However I store my show carry cages on top of other cages, as well as my stock of nestboxes, so it's a good storage area.
I also only use 1x2" wire for the walls, and half inch by 1" for the floor. I never use half by half inch wire because usually it's too weak and rusts very fast, in my experience.
Let's say your roll of wire is 24" tall, just to make it easy. If your wire had been 16" tall, or 18" you would have to cut an extra piece to make the ceiling 24" deep, in order to have cages that are 24x24. In addition the 2 end pieces would have to measure longer as well.
First cut 3 sections of the 1x2" wire that measures 96" long, or 8ft. These will be your front and back walls, and your roof. Next cut 2 sections of the 1x2" wire that measures 24" long, or 2ft. These will be your two end pieces. If you're like most people you're probably cutting this wire by hand, with a pair of snips/wire cutters and your wrist/hand may be killing you. Now you can take a break from wire cutting and set up what you have already.
The easiest thing to do, if you don't have a helper, is to attach the 3 long pieces together, long ways. I use ROSO clips, I like them the best. They are strong, look like C's from the side with pointy ends. Some people use J-clips that look like a J from the side and are thicker. The ROSO in my opionion are harder to remove, and are stronger to hold more weight, which is always good.
So yeah, attach all 3 long pieces together long ways. Take the end pieces and attack them at either end of the 3 attached long pieces. Eventually after attaching several clips (usually no more then 2 inches apart) you'll have what is starting to look like a really long, floorless cage.
Back to wire cutting! We're making this a 4-hole cage. So you need to cut 3 more pieces that measure 24" or 2ft. Here you can use either the 1x2" or the floor wire. A lot of breeders buy solid metal dividers to put in their cages, or plastic ones. These ARE BEST if you can afford it. It keeps rabbits from chewing on eachother through the cage, and sprayers from staining their neighbors. However if you need to set up a row of cages fast, you can always add these later, attaching them to the already inplace wire dividers. (Or remove the wire ones and use them as scraps for another cage.)
You'll have to break out the tape measure and install these dividers via the bottom, 24 inches apart from eachother.
Once they are clipped in, you can go onto your roll of half inch by 1 inch wire and cut out your floor. It should measure 96" long, or 8ft. You can now attach the floor, remember to attach your dividers to both the floor and roof of the cage, so they are in place securely. Some bucks will push on these, and even sag the floor to the point where they can even get into the cage next to them if they are not secured. Same goes for the roof parts. These are harder to get into place sometimes, so I use galvanized wire for the tougher areas, sure to snip off the extra so I don't have anything poking out anywhere.
Now you should have a fully ensembled cage, without doors. Door size is up to you, provided that there is enough room for a nestbox to fit in and out easily (if needed.) I make most of my doors 12x12 or 14x14 to allow for that. You'll have to measure carefully and use a sharpie marker to make your measurements and where to cut.
Once all 4 door holes have been cut out, you have to make your doors out of the roll of wire. Either type is fine, I prefer the 1x2" because at this point, it's usually the easiest to cut. If you made a 12x12 door (measure your opening to be sure you didn't mess up) You will want a 12x13" or 13x13" door to cover up the hole. 14x14 would require a 14x15" or 15x15".
Attach the doors however you want. I prefer them to be attached at the bottom of the opening, so when they open the door just drops open. Some people attach them so they can swing open from the side, but this can cause a problem. Doors left open can be unseen dangers. I've walked into my fair share, gotten my hair tangled in one, and even scratched up from an open door that swings sideways.
You'll need door latches to keep the doors shut. These are usually a piece of metal molded into shape. Attach them as needed to keep your door securely shut. When in a jam, and I'm out of these, I'll use a plain piece of wire to secure a door shut. It takes longer to open and close securely, but is fine for a couple of days for me. I would not recommend anything else, like close-pins, because these can be chewed off, or pushed on to have the door fly open.
Once your doors are installed, with latches. Your cage is basically done. Hooray!!
Now how do you hang it? In most barns people will run 2x4's and make a frame from them to hang from. Other people will have them hang straight from the roof rafters and/or beams. Some people will buy actual chains with S hooks to hang them with. I buy a small roll of wire, strong enough to support the weight. You can buy these in the hardware isle in Lowes / Home Depot near the screws and nails. I can get a 50ft roll for about $6 or $7.
How tall you hang them is up to you. Think of where your floor will be, if you are not pouring cement and are just using the ground, you don't want them too high. Think of how tall you are. Think of how tall you want it if you have predators or dogs to worry about. You don't want the neighborhood kids to wander into the barn and start opening cages that they can reach.
I use the wooden pallets for my floor, that gives an additional 4 inches or so on top of the ground. All of the cages are hung with their floors at least 4ft from the ground. These are at eye level for most adults.
I hope this article helps and if you have any additional questions that I have not covered, please Email Me.