Customize the size of both sides of the wrench. Remember to use the insert size of the nut instead of the outer nut size. I have updated the wrech a little bit so it will be a little more thicker on the outside. I have printed it with a 20% infill and noticed that the PLA is bending a bit, but is gives enough tension to lock the nut. For a better functionality of the wrench you have to increase the infill density.