Looks great...love the colors. Did you put a hard bottom in the purse? If not, you could make and cover one, putting it in the bottom holds the lining down and gives it some stability. I just guesstimate the size, try it, and adjust until I am satisfied with the fit. Plastic canvas is cheap and water friendly. Make a little pillow case cover from one of the fabrics, slide it in, and there you go. Your mom will love that you made it for her.