[Lil Sis]

I have used several, and different ones worked for different needs.
I used the one posted by critter... I find it is a lot less exspensive at toys r us then a pet store!!

I also went to consignment store and bought -- oh like a play pen type pop n play. It was very inexpensive. The girl at the consignment store said they always keep the ones which are a little stained for people who want them for pets. It was reallly cute and I paid like $25.00 and used it when I had my girl and my daughters boy. When they out grew I did not feel bad getting ride of it.
I also have a crate, at this point I don't use a crate but keep her used to it so if the need is there she will go in. In fact she does go in the crate to nap and get away from brothers from time to time.
I also have a portable smaller expen that has a door and is "cute" that I can use. The larger one is now used outside.

Hope that helps