For a couple years I toyed with the idea of making a robot that can draw shapes. Upon becoming a middle school teacher during the 2015-2016 school year, I finally felt the necessity and broke down and designed such a robot. To make room for the marker, I had to replace the breadboard with a printed circuit board.
Version 4 has been tested and works as expected. It is the first Logo Mouse PCB design to accommodate sensors and is fully capable of navigating a maze. The breaks to the 5v and VIN pins were removed - now the mouse is powered only through the VIN pin. As a consequence, you'll want to make sure you buy an Arduino Nano or clone with a decent regulator (anything with an FTDI chip on the bottom generally fits the bill). The left and right sensor pins have also been swapped to make mapping the traces a little easier. You'll need to modify your code accordingly. The creation of your sensors object should appear as follows:
Version 3 modifies the placement of the Bluetooth module so there is room to plug it in.
Version 2 features larger holes to accommodate female header pins for the servos and the screw terminal. Any traces that supply power have also been widened and the placement of the components has been slightly improved. A break in the trace to the VIN pin has also been added (so that a 5v regulator can be used even if the Arduino's VIN pin is still working).