I made this dress myself. It's super simple.
Take a long piece of cloth (1.50 x 2 m)
Fold it in half.Leave slits open on the sides
for your arms to fit through. Cut open the
top for your head to fit through and sew the
rest together. Cut the slits for the skirt part
really big in order to have a more geometric
shape. Et voila. And again, I just do these
things through aptitude. I don't get patterns..