If you're spending this somewhat inclement Easter Monday thinking of project ideas, you could do a lot worse than a Useless Machine. As the name suggests, the machine itself is entirely useless - but the process of building and programming it is anything but, and as YouTube user fritend1's latest example shows it can be an incredibly entertaining time-waster.
For the unfamiliar, a Useless Machine is traditionally a mechanical or electromechanical device featuring a single user-operable switch. When thrown, the Useless Machine activates with a singular purpose: to flip the switch back into the off position. Each time the user flips the switch on, the machine switches it back off again. In its simplest form, the Useless Machine's amusement value is quickly exhausted - but with a programmable microcontroller inside, it becomes easy to add some personality.
Fritend1's particular Useless Machine, built using an Arduino Uno compatible microcontroller linked to three hobby servos, shows off this personality in the above video. As the user continues to 'annoy' the machine, it responds in a variety of methods before eventually waving a white flag in surrender - thought that isn't the end of the battle. It's not the most complicated Useless Machine around - we've seen examples which even run away from the user - but it's a great example of how quickly-constructed objects can be imbued with personality.
Fritend1 discusses the project on reddit, and has a series of images showing off its internals available on imgur. Sadly, there's no build log - though its operation is reasonably self-evident from the images - though the source code has been published on codebender.