Do you also have too many backpacks and no good way to store them? Hang them! All the other models I've found did not account for print orientation for maximum strength.

Print it on its side in the default orientation stl for maximum print strength.

With 4 walls loops and 15% infill, these are incredibly strong and have held up to a 15lb backpack without any issue. I've printed in PLA but should work in ABS as well