Raising rabbits can be rewarding and a lot of work. Rabbit cages are designed to make both your life easier and the rabbits safer. Knowing that your pets or livelihood are both protected should let you sleep better.
All rabbit cages should have mesh bottoms that allow feces to drop through in order to avoid the rabbit becoming sick. A tray should be located below the cages to catch the feces for easy disposal. This should be done on a regular basis (often several times a day), depending on the number of rabbits. It is important to the health of not only the rabbits but also for anyone in the surrounding area, and that includes people.
The cage should be tall enough for the rabbit to stand on its back legs without hitting its head. Remember that rabbits forage for vegetation in the wild and that gene is still very active. If the rabbit is kept in a cage for the majority of the time, it should be taken out a few hours of the day for exercise to avoid health problems. You should have an area where the rabbits are let out to exercise (yes, they need to move around more than just a little).
The cage should be resistant to chewing, and if possible, try to provide a separate space for the rabbit to have a rest area and a place to hide. With the genetic code of a victim (remember, rabbits are a primary source of meat for many predators and the flight mechanism is ingrained in their systems), rabbits tend to do better if they have a secure hiding place. Make sure that they feel safe from predators; they have been known to die of fright. Be sure to provide sufficient room for however many rabbits are in the cage.
All in all, rabbit cages are an important part of your rabbit habitat. You can attach the cages to a secured run or exercise area, but that will be another story.