Do you ever wonder what the status is of individual cells (AA or AAA) when several of these are connected in series like in many portable radios or toys?
To measure this, I took two strips of bronze of which I isolated one side with tape. Then I soldered a wire at the end of each strip and isolated it with shrink tube. At the other end of each wire a socket is connected that allows easy insertion of a multimeter probe. See the photos to get a good idea of how the strips are supposed to be used.
This small part has proofed its usefulness over the years; the only problem is to remember where you put it the last time you used it.