Lego Mindstorms is a hobby kit developed and manufactured by Lego for building programmable robots that use a combination of standard Lego bricks and pieces, a central controller, various outputs such as motors, and some sensors. Hobbyists then design custom robots for various jobs that make use of the kit. The standard sensors available are light, ultrasonic, sound, infrared and touch but hobbyists to build their own custom sensors using reed switches to make their experience more real. Reed Switches can be built into LEGO bricks to sense position and rotation. Position sensors can be built in Normally Open, and Normally Closed types. Rotational sensors can be built with two reed switch and many magnets on the rotating shaft. Pull down resistors are connected to each of the reed switches so that four different voltage level outputs can be given to the controller. Do contact us if you so require reed switches to be built into specific Lego bricks.