Substitute for cardboard when covering walls

Hi, recently I’ve placed cardboard at the bottom of the door (where my chinchilla likes to try and bite the paint). However, now he tries to chew and eat the cardboard during playtime. It upsets him whenever I have to shoo him away from it (which is a lot). Does anybody know of any other cheap ways to cover the wall? Thanks.


Sent from my iPhone using Tapatalk