Rolly Toys Kupplungbolzen/Hitch Pin (Modified for easier printing)

Slightly modified version of original, as that one would detach on my glass-bed equipped printer every time. Added a scaled cube with Blender that extends the bottom layers from 3 thin lines to one rectangular area.

Added geometry at lowest layers so there's not 3 very thin lines, but one single rectangular area, as otherwise I had issues with adhesion on my glass bed.

V2 is even stronger, with the airgap below the lug removed.