blockbag.png
From ( 0,  0) to ( 5,  5): top/bottom bumps wide area
From ( 0,  6) to ( 5, 11): side bumps wide area
From ( 0, 12) to ( 3, 15): top opening
From ( 4, 12) to ( 5, 12): string
From ( 6,  0) to (11,  0): 1 wide strips

Keep the proportions the same for higher resolution textures and all will be fine. (I hope)