Bing Crosby famously sang “Just let a smile be your umbrella.” George Carlin, though, said, “Let a smile be your umbrella, and you’ll end up with a face full of rain.” [BebBrabyn] probably agrees more with the former and used a Raspberry Pi with Open CV to detect a smile, a feature some digital cameras have had for a long time. This project however doesn’t take a snapshot. It launches a marshmallow using a motor-driven catapult. We wondered if he originally tried lemon drops until too many people failed to catch them properly.

This wouldn’t be a bad project for a young person — as seen in the video below — although you might have to work a bit to duplicate it. The catapult was upcycled from a broken kid’s toy. You might have to run to the toy store or rig something up yourself. Perhaps you could 3D print it or replace it with a trebuchet or compressed air.

In our darker moods, we can think of other things we might want to do upon detecting a smile, but that would sort of spoil the spirit of this light-hearted project. We were a little disappointed, though, that there’s no automatic loading of the catapult. Perhaps that will be in phase two.

We’d be more likely to use the launcher for dog treats, but this is a great example of how easy it is to bake Open CV into a Pi project. It’s certainly not as violent as the motion tracking air soft gun. If you want to have a go at replacing the catapult with a pneumatic cannon, you might start here.