So, I know that the “proper” way to get the sleeve-puff look is to sew a separate chemise and allow it to puff through openings in the oversleeve. I’m not going to do that. Instead, blatantly borrowing from numerous online tutorials on constructing sleeves for “Merida” costumes, I’ve constructed the puff and non-puff sections of the sleeves separately, and sewn them in a column to form the sleeve.
To draft the sleeve pattern, I took the basic straight sleeve and marked where I wanted my puffs to be. Then I cut along the lines and re-drew each piece, adding in seam allowances. The elbow puff is tapered at the inside elbow joint so it won’t bunch when I bend my arm. Similarly, the shoulder puff is cut right at the section of the sleeve under the armpit to avoid bunching.