Let's give ourselves a break today and do some easy stuff!
For your flaps, you should have cut 2 of fabric and 2 of lining. The fabric pieces will probably need to be interfaced - I used ProSheer Elegance Light on mine because I wanted to retain some of the softness of the fabric.
Before sewing the lining to the outer, trim 1/8" off the lining pieces at the sides and bottom. Doing this will help the outer fabric roll to the underside once the flap is turned out.
Sew all the way around the sides and bottom. M6172 uses a 3/8" seam allowance here - make sure to check what your pattern uses. Because the lining piece is a bit smaller, it will pull up like this before turning:
Trim the seam allowance before turning. I do this with pinking shears to avoid getting a show-through seam allowance line when pressed. It also can sometimes eliminate the need to notch the curve, although I still had to notch these a bit.
Turn the pieces out and give them a good press, making sure that the outer fabric rolls to the inside so that none of the lining will show. Machine baste the tops closed at 1/4".
Now take the two remaining welt pieces and attach them to the pocket bag piece. Because of the way we did the welt, we only need to attach this on one side. Line the welt up with the pocket bag and stitch at the top and bottom of the welt with a 1/4" seam allowance. Then go back over the bottom stitching line with a zigzag. Alternatively, you could serge this bottom edge - but why get out the serger when the sewing machine is sitting right there?
Press these pieces as well, then set everything aside until tomorrow, when we will put it all together with our previously made welts.