14 year-old designs functioning Lego printer

The printer employs three motors to control the motion of a felt tip pen. Overweel converts source image files into to a text file of 1s and 0s using Paint.NET, which is then (after some tinkering) imported into RobotC - a development environment used to control Lego Mindstorms NXT robots (among other things) based on the C programming language.

Two of the PriNXT's motors control the pen along the X and Y axes, while the third lifts and lowers it from the page. The printer also makes use of two touch sensors, a light sensor and a color sensor. The light sensor is cleverly used to assist with the vertical motion of the pen.