I used sandpaper to get rid of the bumpy plastic on Darwin's bin cage. Also, if you put the mesh on the
inside of the bin, Sammy won't be able to chew on it because the mesh will cover the bumpy part.
Darwin has never broken out of his bin cage however, he isn't really a Houdini or one to chew very much. He really likes his bin. He started out in a Crittertrail from PetSmart because I didn't know any better at the time. After finding HC, I immediately made his bin cage & he's been happy ever since
If you are worried about it, I put binder clips (aka bulldog clips) to hold his lid to the rest of the bin at night, just in case.