The Canelo Project, a family ranch in Sonoita, Arizona, uses the most basic of resources, dirt and straw, to build houses.

Bill and Athena Steen, the husband and wife team that founded the project in 1989, use strawbales as the building blocks for their homes.
They stitch together the bales, and plaster them with a clay mixture that they create themselves.
This process creates a highly insulated, customizable home.
They have written books on their practice, and hold workshops to teach this method to others from around the world.
You can watch a short video at www.youtube.com
Maybe put a rototiller on an excavator arm for mixing mud….or a giant bread mixer…lol…post insulation effeciencies and time factors please.