French inventor Julien Coyne of Mojoptix has engineered a 3-D printed that numerically displays the time between 10 a.m. and 6 p.m. While traditionally sundials were used in ancient times to cast a line or triangular shadow to indicate the hour, this one is designed so that when light passes through it, it displays numbers that indicate the time. Basically, it's magical.
Coyne explains that the shape of the sundial has been mathematically designed to only let through sun rays at exactly the right time and angle, allowing it to display the actual time with sunlit digits within the sundial's shadow. It's even adjustable for Daylight Saving Time.
It's unlikely that the digital sundial will make its way into your local department store, though, and for now they're available only through the inventor's Etsy shop. "The swiss cheese inside the sundial is so intricate, that you can’t realistically use injection molding or some other mass-production method," the inventor wrote in a blog post. 3D printing seems actually to be the only practical way to build this digital sundial."