30" deep by 36" wide by 18" high is the recommended size for NZ and Californians. Although I have seen many people keep them in 30" x 30" x 18' with no problems (these are all wire cages). Having a multi-compartment hutch is different. But hopefully that gives you a good starting point. All my rabbits are in all wire cages.
Also, if you are making a wire cage, many will tell you to put the door either on the left or right side of the front. If you do this, you'll have a heck of a time reaching back to the opposite corner (particularly if 36" wide). My doors are all dead center, with water on one side and feeder on the other (of the front).
Also, if you are making a wire cage, many will tell you to put the door either on the left or right side of the front. If you do this, you'll have a heck of a time reaching back to the opposite corner (particularly if 36" wide). My doors are all dead center, with water on one side and feeder on the other (of the front).