I worked out how to make these from these confusing directions and simplepattern. If anyone's interested, I'll post a tutorial.

I want to make more with Halloween fabric.

I made this one quickly, I needed a little bag to go to a funeral, so it's got some mistakes. That's what I get for making it at 2am with stretchy fabric (which I can say with experience I don't recommend).
What do you think? I want to make a bunch, they're easy and cute, big enough to hold the essentials (I don't carry anything smaller than my Epi-pen). I was thinking of making one with a shoulder strap.
Also found this blog of a guy making wooden wings, which are just gorgeous.