Using leftover fabric from pillow covers and a lampshade that I made, plus a deconstructed floral print Ralph Lauren shirt from the thrift store, this is what I made.
It's roomy and it's reversible. You can see by the wrinkled fabric that it gets a lot of use.
You loop one handle through the other to carry it. Next time I make one, I'll make the long handle a bit longer so that it could actually go over my shoulder.
If you search "boho sling bag" or "Japanese sling bag" on Pinterest, you will see lots of variations.