Readers of a certain vintage will no doubt remember that for a brief time, some alkaline batteries came with a built-in battery tester. Basically, you just pushed really hard with your fingernails on the two ends of the strip, and it either lit up the little strip (or didn’t if it was dead), or made the word ‘good’ appear if energized.
This is a companion discussion topic for the original entry at https://hackaday.com/2024/07/06/2024-business-card-challenge-a-battery-tester-with-blinkenlights/