I have provided a ready to print .3mf file. I have printed this in Bambu Matte Red and Sunlu Matte Olive Green successfuly.
The improved shaft design was modeled in Blender however the new bolt pattern was done in the slicer.
Considerations:
This is stronger tha the original but obviously if you hit it hard enough it doesn't matter, it will break. Again, PETG or some other more suitable material will improve this significantly. I am using PLA because I want red.
The author remixed this model.
This remix tries to improve the shearing strength at the mounting plate by adding a larger chamfer, shifting the stress point closer to the wheel and increasing required the leverage to break it along the layer lines. I've also moved the bolt holes so they are spaced correctly at 40mm.