Since I can't take a picture with it on my shoulder, this will have to do.
Here's a little better shot. I couldn't find a button, so ended up making a covered one with some of the leftover fabric.
I like plenty of storage, so I added pockets on each side of the lining to hold small items.
Finished size: 16 3/4" wide, 12" high; strap 13" long, 4" wide. I hope to have a few of these in the shop by the middle of June... don't know what the price will be yet, but they are quick to make, so that should keep them affordable! Stay tuned...