Main part of the arm is 15mm x 15mm bar (1mm thick aluminium in my case, it is bending just the max amount, I wouldn't go to a softer material or thinner bar), onto to which two hooks and optionally a handle are pushed.
The arm provides mechanical leverage to more easily maneuver with the bike rack.
To print with PLA, it is necessary to print the hooks with so many perimeters that the part is almost solid or use some more exotic material.
Works fine with Thule Epos 3.
The author marked this model as their own original creation.