According to Wikipedia, "A useless machine is a device that performs a mostly useless task, such as switching itself off, and performs no other practical function."
Some good examples are here :13 Awesomely Useless Machines - Urlesque
The goal is to make utterly useless machines out of K'NEX pieces only. Reply if you think you're up for the challenge!
Edited by StuntPilot22, 08 November 2013 - 01:35 PM.