As you can see... it didn't take long for them to grow from the size of a football to the size of a small beach ball. So, after a while of them not destroying the stuff in their pen, I decided it was time to do some upgrades. Staring with all new rugs to give them a nice soft place to relax. The cardboard I had laid out was still clean and in good order, so I just placed the rugs on top for extra bounce. I then built this nice big hide box for them to call their own. The idea being I will never enter the box when they are around, making it a safe place to retreat if they should feel the need. The size of the box was also planned to make it the same height as the window. I leave the blinds up so they can sit there and watch the outside world whenever they like. They love laying up there in the morning when the sun shines through. They have a cute little flannel pad to cuddle on. Because they are getting so big, I also had to upgrade the size of the litter and feed box, making it the full width of the pen. So far they have not been brave enough to leave the pen.... but I leave the door open just in case they want to explore.