I use the small concrete mixing tubs for my rat rack. I leave my males in with the females and babies though and I have no problems at all. I followed this thread for the plans:

http://ball-pythons.net/forums/showt...Rat-Rack-Build!

The small tubs he used in this build are big enough for a 1.2 colony. I leave the babies in the same tub until they're ready to be fed off (usually just a week or two after weaning, the whole litter gets fed off at once). I haven't ever had a problem doing it this way, although you can't really control the staggering of production this way. Some weeks I will have 2-5 litters, some weeks I have none...