This project is awesome, but I'd be worried about my hand brushing up against all that lead every day for years. Or am I being too paranoid? In any case, easily solved with some casting epoxy.
https://github.com/conorpp/u2f-zero/blob/master/hardware/cas...
I do think think a case is necessary though, as those SOIC packages will not last long in pocket with keys before they are ripped off the PCB.