Bringing the concept down to Earth and thinking the construction through.
Refining the details.
Laying out the displays and the date window.
Making a mock-up.
The ergonomics prove defective right away: the watch fits poorly making the band too short.
Reshaping the body and the band.
Designing a pattern for the underside of the band.
Modeling the watch in three positions: sitting on a flat surface, band is relaxed, and all buckled.