Much talk about the pen we use at our own home to foster Rain and Feather; here is a more in-depth look at our cool cage!
The cage has two doors, very useful when you want to grab the bowls to refill without having the kittens run out. Edit: the doors open with the catch on the left and the hinges on the right. The whole door can be easily removed if you need to do some clearing up.
The bottom level we put the litter tray and scratching post with mobile toys. They play with the toys and use the scratching post to strop as well as climb to the top levels where their food is.
They can sleep on either levels.
Addendum: Just made a hammock for them, marinated with catnip, so now they have a third storey to climb to and can access to the hanging post more easily. Also, the price is about $150 from Angels Pet Shop and you can choose which inserts you want for the floor base.