I use Organize-It cube panels to make a pen for my rabbit, Althea. She's a medium-sized rabbit (6 lbs), so a two-high configuration works for her. I tie the panels together using plastic cable wraps that are usually used to bunch computer cables together.

A pen made with these panels can be reconfigured to different shapes, making it okay to have my bun in the living room, where the pen just flows around the furniture. I use the panels to fence off my nicer furniture or to keep her away from certain areas as well. You decide how large or small the pen is by adding or subtracting panels.

When I go on a trip I don't have to take them apart! I fold the pen up and throw it in the car trunk.

A bonus is that they come in two colors -- black and white. After 4 years the white still looks great -- there is no rust or corrosion, and my bun has tried chewing her way out of the pen many times (sorry, kiddo!).

I don't remember the exact cost, but for several (16?) panels, I think it was around $20. I bought a couple of sets and made a good-size pen.

Pros: easy to configure and clean; durable

Cons: can be clumsy and heavy to move an entire pen!

Perfect for building small animal cages! These are cheap and easy to put together. All you need is a bit of ingenuity, a desired layout, and some zip ties. We have multi-level cages constructed for the bunnies in our home. They love being able to hop up on the upper levels and watch all the action instead of being at ground level. Many more possibilities for housing using these instead of pre-made cages. Recommended.

Pros: Cheap, easy to construct, multiple configurations

Cons: None

Good for cages! My buns love them!

Pros: Easy set up, durable

Cons: none