Ok, finally the tutorial. This is the version without pleats (as I had the pieces waiting to be sewn). It's exactly the same pattern but shortened at the top - for pleated goodness add at least 3-4 inches to the width of the top band. You also don't need to shape the bag at the top as the pleats do it for you. If I make no sense whatsoever or your a bit lost then feel free to comment or message me
Alright then, first cut out your pieces - 4 top band, 2 outer, 2 lining and your strap. Interfacing is very important for this bag, especially on the top band so layer it on! I like to make the top band curve down towards the middle and in the interested of the tutorial it'll be easier if I assume that's what you've gone for. Make a nice curve at the bottom of the body pieces - they get pointier once you've sewn them so overdoing the curve isn't a bad idea.
Once the interfacing's on place a top band on a body piece, right sides touching. The curved part of the band should be facing up, the straight part at the bottom. Make sure the middle of the band is at the middle of the body or it'll look all wonky.
Once you've sewn all 4 bands onto your outer and lining pieces grab your two completed outer pieces and places them together, right side up. Match up your seams between the top and body and sew all the way around. Turn right side out. Now do the same with your lining pieces but leave a gap at the bottom (to turn the bag through) and leave inside out. I always stitch around twice and zigzag but if you can't be bothered and it's just for yourself then once should do the trick.
Now grab your outer pieces and place them inside the lining piece (right sides touching). Your outer piece should be right side out and your lining piece wrong side out. Now is the time to put your strap on (hehe, punalicious). Place the strap in between your lining and outer piece (so that it's where the right sides of the fabric are). Pin the tops of the strap in place. Now sew all the way around the edge at the top. Again I tend to stitch this part to death but if it's for yourself I'd reccommend stitching around twice. Go over the straps a few times though to make sure everything stays where it should.
Now for the fun part - pull the bag through the gap you left in the lining, try not to tear anything or pull your stitching apart. Once that's done sew up the gap in your lining (matching thread's a bonus) and put everything in place. Sometimes i sew around the top again on the outside and sometimes I don't - entirely up to you. And unless I've confused you completely you should be done! Here's my completed bag below, with added ribbon-ness and skulls.