I made these “flat pants” (scroll down for pattern) three Halloweens ago. It was one of my first experiments with french seams (which, as it turned out, was a bad idea for the intersection of the rectangular crotch-gusset to the pantleg).
My kids have worn these pants tons over the last three years, in diapers and without. They are currently favoring Nels, and are shorter on HIM than they were on HER in these pictures.
Viva la home-sewn love!