Bouncing is fun. A spring has potential (elastic?) energy that has many uses in our life. Can you think of any uses? I just had a front suspesion replace in my old car. There are two big springs (or perhaps 4, I did not check back wheels) on top of the two front wheels. The two springs make sitting in the car comfortable by obsorbing forces and only bouncing slightly when driving (on rocky road).

In the X3DOM mailing list, there was a discussion about constructing solid geometry. One application of solid geometry is to model the cross section of Earth. Unfortunately, solid geometry is not supported in X3DOM. However, the cross section can be achieved by using other geometry available in X3DOM. Here is an example.

I created a hexahedron (cube), which is a polyhedron platonic shape.