With the help of a friend, I built a rat rack back in February. It has been working great except my rats keep chewing holes in the tubs and just about escaping. I have not had an escapee yet, but I know it is coming. Does anyone have any tips on how to prevent that from happening? Do I need a different type of type, one that is sturdier? I am using sterilite tubs at the moment, the same size I use for my snakes, just because I had them lying around. I can change if need be, I just need help knowing what to get! Thanks in advance!