This maybe doesn’t have the fancy seven segment or OLED display you were expecting though, instead it’s an ATtiny85 with a lithium cell, the minimum of components, a thermistor for measurement ...

But LEDs are far from the only way to run a seven-segment display — check out this mechanical seven-segment display for proof of that. We’ve been seeing a lot of mechanical seven-segment ...

seven-segment display (Image courtesy of LXD, Inc.) In their natural state, liquid crystals line up with the orientation "rubbed" into the front and rear glass panels. The rubbings are microscopic ...