This is the ex-pen I used for my girls until they became more potty trained. You can get extra panels to make it bigger, and can keep their crates in there, beds, potty pads, food & water.
It is light weight and easy to move. I loved having it to take out on the lawn or patio to keep them safe when I was outside. Also great to have a safe place to put them when they were little if company came over and there was danger of getting stepped on.
Now that my girls are all grown up, I use 2 panels of the pen as a gate inside the front entry so they don't dart out the door.
Amazon.com: IRIS Indoor/Outdoor Plastic Pet Pen...