The maze has dimensions fixed by the competition rules. Further, the mouse is limited to a maximum size of 250mm x 250mm. When the competition was devised, this was a fairly significant constraint. in these days of tiny processors with everything on board and handy, small, batteries, it makes sense, even for the beginner, to start with a mouse compact enough to perform reasonably well even running the diagonals of the maze. This picture shows the main critical dimensions we will work to. It will be narrow enough to stand a fair chance of running down the diagonals and long enough to be stable while giving the builder room to place all the components.The heavy components – the motor and batteries – are placed close to the centre of the mouse to reduce the inertial load on the motors and help with stability. Rounding the corners not only makes it easier for the mouse to do an in-place turn, it can help a mouse recover after accidentally nudging the post on a poorly executed movement.Keeping the mouse down to these dimensions is going to be a bit of a challenge. In particular, the width may turn out to be optimistic.