Cut your main fabric piece 27 inches long and 41 inches wide; the trim fabric full length by 1-1/2 inches wide; and the cuff fabric full length by 12 inches wide.
Lay the cuff piece on a flat surface and iron. Place the trim fabric with the right-side facing down along the bottom edge of the cuff fabric. Fold the trim fabric in half with the wrong sides facing and the edges in line with the cuff piece. Iron the trim piece to keep in place.
Line the main fabric's raw edge with the raw edges of the cuff and trim pieces. The main fabric will be about two inches shorter than the length of the other two pieces. Center the main fabric with the excess divided to one inch on each side. Then use straight pins to pin all the fabric pieces together.
Roll the main fabric as if you were rolling a sleeping bag, starting from the opposite end that was just pinned. Stop when about three inches of the cuff fabric shows.
Lift the raw end of the newly exposed cuff fabric over the roll of main fabric and line the edges with the raw edges that were just pinned.
Pull the existing pins out and re-pin to include the cuff fabric that was just folded over.
Use a sewing machine to stitch a 1/2-inch seam all along the raw edge, removing pins as you sew.
Pull the main fabric out through one of the open ends of the roll and lay flat with the right sides facing up.
Fold the entire piece in half with the wrong sides facing and cut off the excess trim and cuff fabric, so the edges are even with the main fabric.
Open the piece up flat again with the right sides down this time. Fold the piece in half with the wrong sides together and line up the raw edges. Pin the edges together all the way down the fabric and along the end. Use a sewing machine to stitch a 1/4-inch seam along the side and bottom.
Turn the pillow case inside out, so the wrong sides are facing out, and use a knitting needle or chopstick to push out the corners. Sew along the same side and end again with a 3/8-inch hem.
Turn the pillow case right-side out, push out the corners with the knitting needle and iron.