The Solar Digital Clock
This 3D-printed sundial uses sunlight and carefully shaped openings to project the time as glowing digits inside its shadow.
As the Sun moves across the sky, light enters from a different angle, so different parts of the internal pattern line up to form different numbers.
Watch the projected digits change as the Sun moves. For accurate time, the sundial must be correctly oriented and designed for its location.
Additional Information
The clever part is entirely in the geometry — no batteries or electronics, just precisely angled surfaces shaping how the shadow falls.
Because it depends on direct sunlight, it can only display a readable time on clear days. Designs like this update the ancient sundial concept, proving shadows can still tell time in surprisingly modern-looking ways.