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Try gerbils. They're 3 times bigger than mice, and if you breed them, they hardly don't smell compared to mice and rats. They are also cute to watch.

My understanding is that gerbils are quite similar to something ball pythons eat in the wild. They are often recommended for getting wild caught ball pythons to feed. This makes me worry that feeding gerbils to a ball python already eating mice and rats might cause it to refuse mice and rats once it has tasted something "better". (I've had this happen with a kingsnake once. Fed him a lizard and he refused mice after that). The problem is that gerbils are much more pricey than mice or rats, and are not nearly so prolific if you are breeding them yourself. So, if you get tired of paying the for gerbils or of having so many more breeding groups and cages around, you might not be able to go back.
Just something to think about.