Here are some photos of theirs from this site:
They built up the corners to prevent escapees.
Here is the puppy cage my storage cube set made:
We took a panel out so she could get in and out and so she would not pee on the floor next to her cage. I have the bottom panels attached and covered with cardboard for extra insulation on the cold kitchen floor. If your puppy is trained it won't bother or pee on cardboard.