By integrating a pair of special wheels internally, the segments can be raised and lowered at will to produce certain digits.
The idea
For many years now, hobbyists have been trying to come up with increasingly unique and novel ways to display information. These have ranged from giant LED matrices to fun machines that rotate plastic panels in order to create various shapes. In this project created by Instructables user gzumwalt, he was able to build a large seven-segment panel that utilizes seven plastic panels which raise up or down to show a digit. However, unlike many other designs, this one only requires a single stepper motor instead of seven, making it much more easily scaled and cheaper overall.