I looked at a couple of stores and didn't find anything so I decided to make one myself.
There wasn't any patterns on pinetrest so I made my own.
The dimensions is 15 1/2" wide 10" tall (not including the strap) and 4" deep. I also used bias tape to finish the edges.
Start by sewing the corners first and then I ironed down the seams. Don't forget to sew in the pocket before sewing the purse together.
Next press all of the seams on the lining and shell of the purse.
Next I sewed the bias tape to put it all together. I've never worked with bias tape before but once I got the hang of it it makes it easier to finish off the edges.