Maybe you already have it covered, but I didn't see a pic of it?
For a 12 bin rat rack, the best advice I can give you is consider going with an automated water system. You won't regret that you did.
Looking forward to the build.
I have a month and a half before I pickup my startup colony. I'm just going to be starting with 1.3, a dwarf male and het females along with 2.8 fancy dumbos. I will be adding automatic watering as the colony expands or possibly just between now and when I pick them up Thanks! We have made all the cuts and are about to start assembly.