Incubator sizes

[Oni5000]

Hi,

I plan on breeding ball pythons next year, so i've got a year to soak up as much knowledge as possible. I'm in no rush to build an incubator, but would like to make sure I know how to do it right when the time comes.

What i'm curious about is incubator sizes. How big are ball python eggs, and how big does an incubator/egg tub have to be for X number of eggs and X number of clutches?

Thanks!