The Numitron was not a failure, though — we know variants of this display ended up in everything from gas pumps to aircraft cockpit gauges. You can even build an LED-based replica clock — no ...

The Numitron was a type of display popular in the 1970s, and often used in aircraft avionics and other high-end hardware. The display is a 7-segment type, but using filaments instead of LEDs.