I know you're gone but hopefully I can save you some trouble when adding the mesh to your tubs.

First, 1/4 will work fine, though if you're making hoppers you may want to get 1/2 to make it easier for your rats to eat. For mice you have to use 1/4 cause they can get out of 1/2 but for rats obviously it doesn't matter both work.

DON'T add it to the sides. If you want better airflow melt air holes in the sides with a soldering iron. I made the mistake of putting mesh on the front of my tubs and all my rats do all day is throw the bedding out the sides. WHAT A MESS!! I'm gonna redo them with mesh lids instead and none on the fronts.
I made mouse tubs as well with no mesh and that works great. No mess.

Melt holes in the sides like I did but do NOT put mesh on the front.
He're's pics of what I did.
For my rats:





For my mice:

see all the bedding on the floor here. I just vacumned!! my rats sit on the shelf above my mice so that's the mess they managed to make in 10mins.