This is how I make a not-so-simple pocket. This one is 3 dimensional, and designed to hold the laptop inside the bag. I wanted a specific spot like this for a few reasons...it further pads the laptop, distributes the weight of it a bit better (to the back of the bag as well as the bottom), and keeps it from flopping around inside the bag. Please ignore the button loops on the top of this pocket in the photos, I later removed them when I realized they were in the wrong place.
The method below is only for pockets that are the same depth on the sides as the bottom.
So. To start, I worked out the width of the pocket and the depth. The width of the pattern piece is left side + front width+ right side + seam allowances (1/4" each side). The height of the pattern piece is bottom depth+ front height + seam allowances. I then cut out the bottom corners - the measurement for the notches cut were taken from the width of the side ( in this case 2" on each edge).
I layered the two layers (lining and outer pocket fabric) right sides together, and batting, then stitched around the perimeter (1/4" seam allowance) but NOT the edges of the notches - see photo above and left. I trimmed the batting to size, then turned the pocket right side out through one of the notches. Then came pressing, making sure that the corners were well turned and pointy and topstitching along the top edge.
Of course why do one pocket when you can do two? I made a little patch pocket to go on the front of this one using the simple method from last post. As in that post, I left the bottom edge unfinished.
To place the pocket:
Place the small pocket lining side up, with the raw edges 1/4" above where you want the bottom of the pocket to be. Stitch across the bottom edge. Flip the pocket up into place and press carefully. Top stitch right and left sides of pocket down, making sure to backstitch well at the top edges to re-enforce. This will help keep the pocket corners from tearing.
If you wanted at this stage you could subdivide the pocket with vertical stitching, or you could just leave it. I left it.
Back to the big, main pocket now:
I turned the bag outside sides together at each corner and stitched the notch edges using a 1/4" seam. I didn't bother finishing this seam allowance as it ended up deep within the bag.
I stitched each corner, then turned them right way out.
More topstitching! I folded the bag along each of its vertical corners, then stitched at 1/8" from the edge to create a vertical pin tuck. Once both sides were done, I did the same to the bottom front edge of the bag.
At this point I had a completely finished 3 dimensional pocket. You'll notice in the photo at bottom right that none of the outermost edges of the pocket are topstitched - yet. They were stitched as a construction seam later, when the pocket was attached to the inside of the bag.
I then set this one aside and made one more inside pocket for the inside front (using the simple pocket method - leaving the bottom edge open).
Just a quick note here, about bag linings: I used to use really dark fabrics to line my bags, but now-a-days use light fabric. The reason being that it is really hard to find anything in a dark bag - especially in a dark room! Light coloured linings make things easier to find, and don't seem to get dirty very fast. The bonus about making this style bag is that I can throw it in the washer if I need to, too.