Those box things at Eren's hips. We're going for a super deformed version anyway.
First, I sketched a (definitely not to scale) maneuver gear box on some newspaper. With the general shape and size in mind, Sak helped me re-draw it on the computer. I printed and cut out the shapes, which fit on two pieces of paper, and taped them together for my "pattern".
I also cut two more pieces of grey fabric, in a small rectangle shape, to use for the pocket. Now, you could also make a proper purse/bag by making an entire box covered in fabric - but I only needed to hold a wallet and a phone, so I went the lazy way with just a pocket.
|This one is just one rectangle folded in half, but 2 pieces of grey work as well. You just want to be able to turn the unfinished edge in after you sew.|
Pin it where you'd like to one of the "backsides" of your main grey fabric, and sew down.
|(This is actually a pic of the second bag, which was mirrored, but you can see how I sewed around the whole thing leaving the left side open.)|
|Had to trim this foam because I didn't leave enough seam allowance :P|
Sew up the open back. I used hand stitching since the foam wasn't co-operating with my machine.
Next, I ironed on a black heat transfer vinyl sheet I cut from the computer using the template shape we created. The vinyl was cut in 2 parts, and overlapped. (More on heat transfer vinyl in my Hataraku Maou-Sama tutorial).
I was worried the iron might melt the non-cotton fabric, or the foam underneath, but no melting occured (YAY). There was a bit of stretching between the vinyl and the grey fabric, but it's not too noticeable.
Anyway, I still have the template file, so feel free to shoot me an email if you'd like it. The cut file is fairly simple and could probably be done by hand, or even with fabric paint instead.