Rat Birthing Rack Plans

[mp27006]

I was looking for some birthing rack plans for approx 16-20 tubs. I currently use the small concrete tubs for the colony but lately Im having issues with moms fighting over pups and general disorder with the litters. I can figure out how to build the rack but need some help with what tubs/bins that will work without being able to chewed out and have a good lip that will work on rails. Below is my current setup. Thanks

[snakesRkewl]

Chewers become instant food, I won't keep any chewers because they teach the other rats to chew.
I use 20qt sterilite tubs for my momma racks, they can be chewed through but have only had one momma do so, and per my first sentence, she was fed off immediately and her babies spread to other momma rats.

[ImBooBy]

Here is my setup. The maternity rack is built using cat litter pans. you might think its too shallow but it works great. babies can reach food when they wean out and moms feel safe in a tight space. as a result, babies grow alot fatter than leaving them all together with other females

[MarkS]

Here is one of mine.

It uses cat litter pans for the tubs.

Front

back

side

closeups of rails.