Here's a sampling of some of my past and current rabbit cages. I'll have to dig up some others from pre-digital camera days. Among bunny owners, the NIC cages and x-pen cages are quite popular for their size, versatility, and relatively low cost. There are many options for housing indoors.
The cage you see immediately below may see rather small, and it is. HOWEVER, it's workable because of the huge amount of time the cage is left open. Every day, without exception, the door is open first thing in the morning and stays open til midnight.
Below are several more photos of the NIC cage shown earlier.
More ideas for indoor housing.
While the photos above (and on the rest of this site) are just of some of my own past/current set-ups, the possibilities are endless. Below are some other creative options that may inspire you to create one to your own tastes.