Waterproof fabric?

[eiaeae.livejournal.com]

Hello friendly crafters!! I figure that in all the creative people in here, there must be some parents...and in those hypothetical parents, there must be some that cloth diaper...and since those imaginary cloth diapering parents are oh-so-crafty, they must make their own diapers, covers, etc...and surely they'd be able to offer me some advice... :)

That said, if those people don't exist outside my head, I'm sure one of you other craftgrrls will have some insight to offer!

What I'm looking for is a material(or fabric? I can never remember which is the right word, even though my costume designer pounded it into my head last year!) that is waterproof...something for making a cover to go between the clothes and the diapers to keep the wetness from getting through... I know there's something called PUL(i can't remember what it stands for, silly me)that is used to make the diaper covers that you can buy... but I was thinking surely there's something(like flannel or fleece?) that can be made to be waterproof?? something?? anything?? haha...help?

Edited to add: Poly-Urethane Laminate !! That's it! That's what I'm looking for an alternative for, haha. :)