Button trouser fly draft & pattern pieces.
With right sides together stitch along bottom edge of fly extension, turn through, poke out the corner & press.
Sew fly extension onto the left front, overlock & press seam allowance towards the side seam.
For the front right side; separately overlock crotch seam & raw edge of the fly extension, sew them together. Press seam allowances towards centre front & stay stitch on top of the fly & press under.
Iron interfacing onto button fly , press in half & overlock. Mark & sew button holes onto the button fly & pin in place positioning it 2mm in from the outer edge.
Sew the front crotch seam from inside leg to where the fly extension & button fly meet, do not sew beyond, reinforce with a backstitch & clip the seam allowance into this point.
Press the seam allowance flat in same direction as the fly extension. Below shows how it looks inside and from right side before topstitching is added.
Topstitch the fly and button fly in place, make sure the fly extension is kept out of the way. Next topstitch the crotch seam, the fly extension can be caught in with this stitching too. Finally catch the corner to the button fly to keep it in position.
Sew on the buttons.
This sample fastens the women’s wear way (right over left), for men’s wear (left over right) follow instructions from the start attaching the fly extension to right front.
Garment Construction 