Figure 1-8 The motors and battery box glued to the inside of the box The motors and battery box are fixed to the bottom of the case, at either end, leaving room for the Arduino and shield in the middle. Step 5. Cut the Case Bottom and Fix the Castor Figure 1-9 shows how the case bottom is cut to allow the top of the gear motors and their drive shafts to protrude from the bottom of the case.
Figure 1-9 The case bottom It is also a good idea to make a hole close to the Bluetooth module so you can see if the LED on the module is flashing or solid. The box used by the author was reused from a previous project and had various holes in it. This is not a bad thing as it allows ventilation. The castor is merely the smallest castor the author could find at the local hardware store. This is just glued to the bottom part of the case.