The passion would be evident with this idea, for sure. However, I feel as if the idea is lacking substance. Ask yourself "Why?"...
For Engineering, if you wanted to construct something from scratch, I would suggest you have a reason behind it that makes the examiner think...
For example, making an affordable means of transport without the use of fossil fuels. Doing a renewable energy project and illustrating how important renewable energy is to society and for the future would be an excellent idea.
Or perhaps a Life-Hack project...I hear they do exceptionally well with the examiners as they have a purpose...
Good Luck