I finally took a minute to see if the nb darling pattern I sent to some people would make a good AIO instead of a fitted. I put PUL outside, microfleece inside. I used 1/4 inch lastin just because I think it does so nicely sewn blind in this kind of diaper and its got such a nice soft gather. I would assume knit elastic would work too.. just not gather as much. I also didn't use the smallest snap setting because there's less stretch in PUL . And made a quick dry lay-in soaker (could be snap in but I was lazy). It turned out SOOOOOOOO well! It fits my daugthers smallest baby doll (which I would very much consider the size of a preemie) and my daughters largest doll which I usually judge to be in the 15lb baby size range when playing. It's AMAZING! It fits trimmer than a kissaluvs and doesn't need a cover. I keep thinking it looks kind of like a FCB 0 AIO, but it's front snap instead of side. Anyway, I think these will be the first diaper I reach for in the first couple of weeks because it has a snap down and won't need a cover. I'm so excited. I'll post a picture later.
Just wanted to say that it does indeed work well as an AIO pattern too.