Here are a few sizes cut out and laid over each other.
Here is the Medium with the edges serged and the first elastic guide seams sewn.
The elastic casings are all sewn.
Elastic installed, front closed, and then wing snaps added.
Here are the finished M, L, S, and XS all together.
Templates can be downloaded here: http://prefold2fitted.blogspot.com/2012/10/online-free-downloads.html