The sticker vending machine arrived at 3pm on a Saturday. By 4pm, there was a line.

We'd brought it as a curiosity. It sat beside the booth looking like something from an arcade, and we assumed it would be a nice extra for the kids while the adults did the serious business of having their photograph taken. That is not what happened. The line was mostly adults.

Everyone loves stickers. This is not a controversial opinion.

What we underestimated was the dispense. You take your photo, you choose your sticker, and then there's a pause, a mechanical clunk, and the thing drops into the tray. That two-second gap does an enormous amount of work. A print handed to you by a person is a transaction. A print you have to reach in and collect is a small event, and people queue for small events.

It also gives people something to do with their hands, which matters more at a party than it sounds. The hardest moment at any event is the twenty minutes after arriving, when you've greeted the host and haven't yet found anyone to talk to. A machine that requires you to press a button and wait is a perfect place to stand during that twenty minutes, and it puts you next to a stranger doing exactly the same thing.

Then there's what happens afterwards. A print goes in a pocket, and a pocket goes in a wash. A sticker goes on a laptop lid, a water bottle, the back of a phone, a notebook somebody carries to work — and stays there. Months later it's still doing its quiet job of reminding someone about a Saturday in April.

The other thing we've learned is to put the event on the sticker. Not a logo — a date, or a name, or whatever in-joke the group already has. It costs nothing to add and it's the difference between a sticker somebody peels off next week and one that's still on a laptop at Christmas, quietly explaining itself to everyone who asks.

We now bring the machine to almost everything. It's the smallest thing we own and it reliably outperforms equipment that costs ten times as much, which we've made a sort of peace with.

If you want one at yours, tell us about your event. Fair warning about the line.