As part of a Service Prototype, we'd asked our model-maker to make up a buzzer. This was so that in a service we were prototyping, we could test certain scenarios that would otherwise been initiated by technology that we didn't yet have in place.
We were faking it.
We tried shouting, we tried a whistle - but we wanted a buzzer. Switch, battery, buzzer, case and tape. It all worked a dream.
After were were finished, the little buzzer stayed in my back-pack.
A few days later I was about to go through Airport Security when I thought I'd check the contents of my bag. There was a craft knife, a screwdriver, some hand gel and a bottle of water which I removed.
I also thought it best to leave the buzzer out.