You could try wrapping the bottom edge of the cardboard with some sort of strong tape to deter them from chewing it. I might try duct tape but if she tries chewing the duct tape, I would remove it immediately because the strings in duct tape could cause some problems. If she's still going at it even covered with tape, you might need to find a more chew-proof material for their playpen walls. I've never had luck with using cardboard as a barrier.

 

What do you use for a barrier? I would love to know. I have duct tape on the corners and she doesn't chew it but it could be different if I cover all the bottom in it.

I'm thinking theres these big white square plastic panels that I had in a old guinea pig cage could work if I could some how put them together standing up... But what do you use or think???

 

I use clear plexi but I've also used coroplast and hardboard in the past.

I would start with taping the cardboard. Maybe that will do the trick. If it doesn't, maybe try the coroplast. Let us know what you try and how well it works!