I disagree. I have 5 kids and while of course you should change your child's diaper often- sometimes things come out so fast and so much at once that the diaper simply does not absorb it. Then you have a super leak.
I also hate to be the downer here but I would not make the castle. I personally don't like those diaper cake things. The reason is that I hate the idea of someone touching etc. all the diapers. It seems gross to me and I probably would not use the diapers. I know some people love them but I also know plenty of people like me that don't. I would hate to see you waste your money on something that the mother may not use.
Oh yea- I used to love Pampers but they have changed them so much that I no longer use them. I use 7th generation or Nature's Best. They have no chlorine etc. (Pampers were giving my child a rash) and they absorb better. They are also better for the environment and they are cheaper which are added bonuses.