Reader [Joshua] sent in his latest project. using a sonar rangefinder, an Arduino, and some clever programming, he’s made is computer react to his distance from it. As you can see in the video after the jump, he has programmed it to change text size and background color depending on his distance from the screen. While he admits that his implementation doesn’t seem immediately useful, there’s lots of potential there. We can actually think of several uses. What would you use it for?