Very simple robot plays xylophone using one LEGO® Mindstorms NXT servo motor to move forwards and the other one to lower and lift the bat. As every NXT robot has to hold an intelligent brick, XP2M is designed to drag it as a trail on 4 cog wheels that can’t turn left or right. Every time the robot moves from one metal plate of xylo to another it plays a tone. Though it wasn’t programmed to play some melody, that could be done if you figure out how to control its speed so that the played tone has a certain duration before another one is played. Program was written in LEGO’s vpl NXT-G.