This is how the nappy looks on the wrong side. when u want the outer fleece to roll in, as u sew the legs u sew as picture above. u still sew normal seam allowance on the outer fleece but take a larger allowance on the inner layer microfleece. trim the excess microfleece when u are done.if u have a cotton outer and want the inner layer microfleece to roll out to prevent wicking u can do it the opposite way (a larger seam allowance on the outer layer fabric instead).
so when u flip it to the right side, this is how it looks (photo above).
The benefit of roll in outer fleece is to avoid wicking. and for sewing the roll in outer fleece this way, it gives your nappy a nicer finish. There's no excess microfleece gathering and less bulky.
This is how i attach elastics on legs (sew the both ends only). photos below are without sewing elastic casing.
I made casing for the elastic just to see what the difference is. Because my pattern is trimmer i find that it's much better to have the casing. Bubblebub AIO doesnt have casing for the elastic. i guess it works fine because the nappy is much wider than my pattern and the material is heavier than mine.
i just found another lady who have a tutorial on this on flickr. it's called Camocotton on PUL here's the link . Her tutorial is on roll out inner fleece to avoid wicking if you are using cotton material on the outer layer.