Realigned the bottom hole of back_standalone_bracket_2021_07_16.stl . Was off center for the back_standalone_left and back_right_raspberry_pi4 files.
Made a nut mount on the extremity_left_mk3s_2021_07_18.stl. It was missing to mount the back_left_2021_07_13.stl to it.
The author remixed this model.