Canniel, I am planning on doing the same thing. I bought a Fuzzi Bunz nappy and am copying the pattern off that as the prototype I made from an internet pattern didn't seem snug enough around the legs and it was a velcro one, when I would prefer to use the plastic snaps.

The Fuzzibunz style have a layer of micropolar fleece next to the baby's skin and this is supposed to draw the water into the soaker that you put inside the nappy, as thick as you need it to be.

One question for you thou Canniel - where do you get your waterproof fabrics? I have ordered some PUL but had to get it from America as I couldn't find it anywhere here.