Outdoor cats get to massacre untold millions of mice per year, but indoor cats have to make do with balls of yarn and laser pointers. To try bridging the gap, one man built a machine that would only feed his kitty when he 'hunts' down an RFID-chipped plastic ball.
Ben Millam made the device in an attempt to bring his cat "one step closer towards a more fulfilled and self-actualised indoor kitty existence". He first considered hiding bowls of food around the house, before realising that was a terrible idea, and coming up with plan B: a feeder that only dispenses food when an RFID-tagged ball is inserted. Millam then hid the balls around the house, requiring Monkey to find the balls if he wants food.
The feeder was made by taking a Super Feeder, and adding an RFID reader, and an Arduino board to control the whole thing. The cat also took some hacking -- felines are normally dismissive towards small lumps of white plastic. Millam had to clicker-train Monkey to pick up the balls and put them into the reader. She eventually got the hang of things, and now resides in a happier indoor kitty universe.