Looking at the pattern, without a zipper it will be open all the way across the top and a button might not close it as securely as you want. You might need a flap to come over the top from the back and button in the front. I can just visualize my stuff falling out before I get it all in or worse than that, I can get it all in but it's scattered all over the floor of a store because that's when it decides to fall out. It would depend on how big you make it maybe. A wallet size is what I"m thinking of, a larger bag might not scatter my stuff like that.