Guidelines on how to make this at home are also available online
French inventor Julien Coyne, founder of Mojoptix, is behind this innovation. Sundials –the world’s oldest clocks- usually cast a line or triangle to indicate the hour, but this one is designed so that when light passes through, it displays the shapes of numbers. Its design is so detailed, that 3D printing is the only way to easily manufacture it, even though it still takes about 35 hours with a fast 3D printer. The clock counts in 20-minute intervals, from 10am to 4pm. It works perfectly in the northern hemisphere, and is adjustable for any latitude.
The only down-side according to the North American Sundial Society (NASS) is that the dotted numerals have light tunnels placed too close together, resulting in an entrance angle of only +/- 15 deg. Since the sun annually moves +/- 23.5 deg. in declination, this clock will not work when the sun heads toward the summer solstice (from about 1 May to 10 Aug) and likewise is unusable during the winter (from about 5 Nov to 5 Feb).