A very easy pattern manipulation for a stunning effect!
Choose you favorite crisp fabric – taffeta would look faboulous, but also a shirt cotton will look great – and start sewing this beauty!
Start from a basic block with dolman sleeve and no darts. widen the neckline, draw the new sleeve length and a slanted slash line in the body.
Then draw some slash lines from it to the sleeve hem.
Cut the extra and then through the lines.
Spread the pieces to give fullness to the sleeve.
Redraw both pieces and mark the gathering/drawstring at the sleeve hem.