A few people asked for an elastic pocket tutorial when I posted my last diaper bag. I tried to explain how to do it in words but it got confusing so I decided to make another diaper bag and take pictures along the way.
First off, here's where I got my material and here's what I turned it into:
And here are the pieces you'll need (the 2 inside pockets are not shown).
Here's the side pocket tutorial:
Stitch together the outside and lining fabrics, fold them back so the right sides are facing out, then stitch in 5/8 of and inch along the edge. See how much space you'll need for the elastic and make a channel. I sew it with the elastic inside (just don't sew over the elastic!). You can also make your channel and insert the elastic with a safety pin.
Lay this on top of your side panel for your bag and stitch one side to the panel. make two folds at the bottom unitl the pocket fabric is the same width as the panel. Sew the bottom and other side of the pocket to the panel, making sure your elastic isn't too loose that it hangs open or too tight that the panel buckles and you can't get your hand in the pocket.
Sew front, back, and side panels to the bottom of your bag, then stitch up the sides. Set aside and start on the lining.
Here's how I do an elastic gathered flat pocket:
Use a piece of fabric that's wider at the top. Make a channel for the elastic (like on the side pockets). Gather to your desired width and lay flat on the fabric to which you are adhering it. Fold in the sides and stitch down. You can leave the bottom open because that will be sewn to the bottom of the bag.
Stitch up the sides and combine with outer fabric. Add the strap, make an opening in the middle of one of your lining sides and pull through.
I also made a changing pad/play mat filled with batting that goes in the inside flat pocket.
Alrighty then, I hope that wasn't confusing. Forgive me if I'm not very good at tutorials. If you have any questions I'll be glad to answer them.