The mouse design exercise looks at the design and build of an electronic mouse that follows a track and completes a circuit in the fastest time possible. The mouse must go round a standard track under its own power and guidance. This is an electro-mechanical system design project that will be built and tested in a real world environment. The track carries a one amp guidance signal at 20 KHz. This will be used to direct the mouse around the track. It will be between ten and twenty meters long. It consists of a number of challenging features including long straights for speed testing, hills with a maximum of 15 degree slope, some corners onto and off hills and corners with a minimum radius of 1.3 metres. The project makes use of differential chassis using the speed of the motors to control the direction of the mouse. The project looks at multiple design considerations and uses a final design that is tested and works to an adequate degree of success. The investigation looks at many designs considering the advantages and disadvantages. The most appropriate design was chosen, built and tested. The analysis looks at how to test and fix problems with the circuit. The project concludes with a mouse that is built and works. The mouse design did not produce the fastest speed as the sensors did not seem sensitive enough so the mouse had to be slowed. There was also the slow down on the hill around the track as the hill control worked but a better electronic control could have improved this. The final remarks include considerations on how to improve the mouse performance.