Can anyone help me with this science(chemistry, physics) project proposal....

To make a working model/ project you will need to be clear with what is being taught in the subject. Once you do that, look at the real life applications of what you have been taught in the same. Using that you will easily be able to make a working model based on application of the concepts taught.
I would suggest to apply your mind and innovation in the project/ model with dedication. This will help you to innovate new project/ model by your own without much difficulty and you will start enjoying making good projects/ model. I hope you will come up with impressive project/ model.