===================================================== LEGO controllers for prototyping; fast, cheap and fun ===================================================== *Janne V. Kujala, Asko Soukka and Matti Katila* We show how custom controllers can be built cheaply, with minimal requirements for mechanical and electronic skills, by using a standard computer mouse and LEGO bricks. The utilization of commodity components allows anyone to reproduce a particular design without any tools and to easily prototype new designs. Our main contribution is a simple, practical and reliable way of interfacing LEGO bricks to an optomechanical computer mouse. The internal mechanism of the mouse is utilized as far as possible, and a small rubber tyre is used to drive the mechanism from the outside, pushed towards the workings with a small pressure. We present two controllers as examples of what is possible within this framework: a controller with two levers and a horizontal wheel, and a joystick-like 2D controller with enough friction to retain the position it is set to. Image series: |Building-1|__ |Building-2|__ |Building-3|__ |Solutions|__ |Connection-solution-1|__ |Connection-solution-2|__ |Joystic|__ .. |Building-1| image:: images/controller/thumb/building-1.jpg .. |Building-2| image:: images/controller/thumb/building-2.jpg .. |Building-3| image:: images/controller/thumb/building-3.jpg .. |Solutions| image:: images/controller/thumb/solutions.jpg .. |Connection-solution-1| image:: images/controller/thumb/connection-solution-1.jpg .. |Connection-solution-2| image:: images/controller/thumb/connection-solution-2.jpg .. |Joystic| image:: images/controller/thumb/joystick-controller.jpg .. _A: images/controller/building-1.jpg .. _B: images/controller/building-2.jpg .. _C: images/controller/building-3.jpg .. _D: images/controller/solutions.jpg .. _E: images/controller/connection-solution-1.jpg .. _F: images/controller/connection-solution-2.jpg .. _G: images/controller/joystick-controller.jpg __ A_ __ B_ __ C_ __ D_ __ E_ __ F_ __ G_ `Low-resolution movies`__ .. _movies: movies/ __ movies_