It's essentially the same pattern and with some variables. And once you get the idea, you can make the perfect bag to carry you life in.
If it's your first time making a messenger bag, this is a good pattern to go with since it can be pretty forgiving, but, like most utility sewing, it can be rough on a machine if you use heavy weight fabric.
*** Per the urging of my friends, I've got a couple of bags up on Etsy that you can check out here ***
Step 1: Materials
I wanted to make this bag a bit tough, so I used a marine vinyl for the lining so I could just wipe out the smushed peaches after riding home from the farmer's market. For the exterior I used a nylon that had a waterproof backing. It was the only thing that was the right color and weight... and it was on sale, so there you go. The price can vary wildly on fabrics depending on where you go and what you select. This pattern will work with almost any fabric, but works best mid to heavy weight.
If you use 54" or wider fabric, you can get away with a half yard for each the lining and exterior.
Thread: I forgot to put thread in the pic, but you'll need it to match the colors of your bag, lining and stripes.
The pattern is dead simple for the main part of the bag and pockets. It's a rectangle that is 41"x18" with rounded corners on one side. I use a bowl to make sure the rounded parts are even. If you're only making one, you don't even need to make a pattern, just measure it all out on the fabric.
Strap wings: I recommend making a template for these. Draw a right triangle at 10.5"x7.5". Use the same bowl from above to round out one side of the triangle and then snip the bottom of the the other side so that there it is 3/4" across.