For birthing tubs (individual birthing) I use freedom breeder http://www.freedombreeder.com/shop/fb10-5 for breeding and communal nursing I use concrete pan http://www.homedepot.com/p/Medium-Mi...101A/202086173

The key for your rat not to chew is to is to put a piece of 2x4 in every tubs , and if you do have chewer you need to get rid of them and their tub mates as they teach one another to chew.