Ben Brabyn wanted to encourage his friends and family to smile a bit more and so he came up with the solution: marshmellows! A Raspberry Pi and a webcam are used to detect a smiling face and then a hacked toy catapult is used to launch marshmellows at the user. He’s used a MotoZero motor controller from The Pi Hut to control the catapult and then written some Python code using OpenCV to read the image from the webcam and detect the smile.

You can see it in operation in the video below and read how to do it yourself on this Instructable.