As I mentioned before, we built a special harness assembly board to teach new operators how to apply spiral tape to a harness. We wanted to be able to time them as well so we could see improvement etc.
They wanted a timer that would be activated when the operator picks up the tape, and deactivated when the operator puts it back.
So I used a make controller, and a sparkfun LCD screen to do the job. I built some firmware that would do the timing. I connected a light sensor so that when light was detected in the holder, the timer would start, and then stop when it went dark. See it in action below!