Indoors is the best place to keep a rabbit, and here are a couple of excellent indoor structures that local rabbit owners have created or modified for their pets:
An extra large dog crate with a wooden shelf zip-tied to create an upper shelf
A mat (or towel) for extra traction can be placed in the bottom tray.
A standard exercise pen
This owner used unfinished 1x6s for the frame. The floor is 3/4 inch plywood cut into two pieces to make it easier to assemble. The pieces are wrapped in outdoor carpet. The owner reports that: "I love this set-up, it works nicely to give her good footing and the frame helps control runaway hair and the occasional fecal pellet".
A homemade (or purchased) hutch
The floor is linoleum for easy cleanup, but there are towels and mats for added traction. This homemade hutch has a shelf for jumping up and is raised up so the rabbits can rest underneath.
Being kept outdoors can be rough on a domestic rabbit. There are many downfalls such as:
Bugs – ear mites, fur mites, and fleas are the most common, but mosquitoes and other insects carry deadly diseases.
Predators – hawks, owls, and foxes often aren’t seen unless there is prey around, such as a rabbit. Dogs and cats can also frighten a rabbit, literally to death. Heart attacks and shock are the top causes of death in pet rabbits.
Weather – maintaining a comfortable, stable, or even acceptable temperature outdoors can be very difficult, especially in summer. Winter rains, wind, and cold can produce respiratory problems quickly, and heat exhaustion can be quickly fatal when unnoticed while at work or school.
Socialization – a pet rabbit that is not near its family is not as tame or sociable as one who sees its humans and interacts daily with them. A rabbit is a social animal that lives in groups in the wild.
Rabbits do great in average household temperatures. However, be sure not to place the cage in direct sunlight. Temperature extremes should be avoided.
A cage can be made of many materials, including plastic and metal. Wood is not a good choice, as it absorbs urine and odors and is difficult to sanitize. If you are really set on wood, make sure you line the bottom and partially up the sides with a non-absorbent material, such as linoleum. Ensure there are no cracks between the floor and wall portions, otherwise matter may collect there.
Wire-bottom cages are not a good choice for rabbits. Wire bottom that is far apart results in stubbed toes and sore joints. Wire that is thin hurts to sit, stand, or lay on. If this type of cage is used for medical or sanitary purposes, be sure to provide a solid area for relief (plexi- glass works well). Also, cecotrophs (stools that are eaten and necessary to the rabbit's health) cannot be consumed if they have fallen through the wire into a tray below
Some new cages have plastic grated bottoms. These are much better than wire bottoms, but toes can still be injured when hopping around.
Bottom line: solid bottoms are best.
Lastly and importantly, the cage should be large enough so that, at a minimum, the rabbit can stand up, lie down and stretch, and take at least 3 strides from one side of the cage to the other.