Some of the materials you may use for shaping the hulls might include a sharp knife, a hacksaw, a rasp or sandpaper. To ensure you don't inhale any dust, wear a dust mask when sandpapering. A battery may power many of the electrical items you use at home. That means that there has to be a continuous flow of electricity and each part of the circuit has to be connected up. A battery has a positive and negative end.
Electricity flows from the positive end of the battery around the circuit to the negative end.
If you want enough power to operate an even bigger appliance, you could use a bigger battery or use more batteries. As long as all the batteries are connected together in the circuit, you will be able to power the device. You should always connect the negative battery end to a positive end. Your model solar boat will not operate with batteries. Your solar panels will trap light and turn it into electricity to operate your motor.