Place the second gusset piece good sides together on top so that it lines up with the first gusset piece. The rolled-up front and back pieces should be sandwiched between your gusset pieces.
¡Buen trabajo! Técnicamente puedes dejar los bordes en bruto, ya que los tejidos de tejidos no se frustran, Pero para ayudar a que sus undies se mantengan arriba, probablemente debería añadir elástico a las piernas y la cintura. Sigue adelante.
Overlap the edges of each piece of elastic by your seam allowance and stitch together. You should have three elastic pieces: one for the waistband and two for the legs.
To ensure that you stretch the elastic evenly, divide the elastic into four quarters and mark the points with pins or chalk. Do the same to the waist and leg openings, marking the quarter points.
Pin the elastic to the waist and leg openings on the good side of the fabric, ensuring that you line up the quarter markings. If your elastic has a decorative edge, make sure that you line up the plain edge (not the decorative edge) of the elastic to the edge of the fabric. The decorative edge should be pointing towards the garment, not away from it.
Sew the elastic to the garment using a zigzag stitch. You will have to stretch the elastic slightly as you sew to make it lay flat against the fabric. Avoid stretching the fabric itself.
Fold the elastic and fabric to the inside, enclosing the raw edge of the fabric under the elastic. You should be looking at the outside of the undies, a folded edge with a bit of the elastic peeking out. Sew using a zigzag stitch.