How about the square bag with handles on each side . It can be carried with either short or long handles or used to store items in. Just make 5 squares the same size and the two sets of handles short set hold in hand length and two long for over the shoulder.
Join 5 outside squares place handles on the top . Make a lining same size as outside leave a 6 inch gap in a bottom seam sew around top ensuring you take in handles safely
Think it is a based on a moda pattern.