Wear

One idea could be to make the assembly (PCB) in a way so that interchangeable watch wristbands fit on it. Some light research on this yielded the result that there is approximately as many wristbands available as there are stars in the universe. They come in all shapes and colors and as amazing as smartwatches are, I think the good ol' watch will stay for a while and so will its aftermarket.

There seem to be a different sizes of the little spring-loaded shaft that holds the band but some seem to be extremely popular and widespread. This would make it so that we could design for this size and then any user can simply buy a fitting band.