As of April 2015, Popular Mechanics offers instructions for building a simple robot on its website. Information on the parts needed for the project is available on the Robotics Universe website.
When completed successfully, the robot is able to navigate rooms, backing up and switching direction when it encounters an obstacle. The robot even makes an apologetic sound when it bumps into something or someone. The robot relies on an Arduino microcontroller board powered by a 9-volt battery.
Popular Mechanics estimates the cost of building its robot at under $100, and the time required to assemble is under two hours. No special tools are necessary.