Project in cesiumjs using webpack bundler

I am using cesium webpack bundler to run cesiumjs on my system. I want to do physics based modelling and simulation. I am unable to figure out how to make sandcastle examples work for our own customized projects and how to incorporate them into our scripts/codes in local machine. A little help will help me get started in using cesium for my 3d GIS project work.
I have attached my files on which i have attempted things. (6.0 MB)