Silicone Molds and Gummi Cast
It would be fun to somehow find function out of this process - like making a tool or container.
It seems like the Geodesic dome is an economic way to build a structure (survival skills). It would be good to talk about the physics and pay tribute to Buckminster Fuller.
Honey Comb Structure
This one is structurally economic and is from bees.
Why not? Seems short, and its always good to know what things are made of.