Meet Bob, the goldfish (pictured below.) Bob is a pet at work, and we needed to keep him fed over the Thanksgiving break. I had an Arduino and a servo that were free, so I wanted to make something that would supply him with the right amount of food for the four days we would be gone. I came up with a little cylinder that I 3D-printed with a MakerBot Replicator v1. It is sized to fit the plus-shaped servo arm attachment for a 9g micro servo. The cylinder features five pockets that food can be placed in. The servo rotates to drop food from each pocket independently.
Below is a video showing the basic usage. Simply hold down the button until the first chunk of food drops. At that point, the food will drop once a day for four more days.