I had a Pachinko machine with a broken and missing plastic lever piece on the inside. It's basically a little arm that pushes down on a cherry switch to tell the computer that there are balls in the hopper.

I confess that, instead of 3d printing a proper new piece, which I easily could have done, I super-glued a plastic piece I took out of a mechanical pen to the broken part of the arm... and then I forgot about it. And then a few years later I sold it. Occasionally I wonder if the new owner has noticed it yet...