Thanks to Marina for this Frugal Baby Tip!
You could try making a double layered fleece pull on. Then you could just run the elastic all the way around the top and all the way around the legs between the layers, by sewing in a casing and threading the elastic through.
You could get a very good fit this way. You could use a cheapie pair of plastic pants as a pattern. Nothing should be able to get out of one of these.
Category: Diaper Sewing