Ferro-Cement, also known as ferro-concrete is a method of building very strong structures. It is made from plaster (sand and concrete, usually) and layers of chicken wire.
This first link is a first person account of the author's experience with ferro-cement. He was cash-flow poor, so this is doable.
Ferro-Concrete Structures
http://www.i4at.org/surv/ferro.htm
Ferro-Cement Boats
http://www.ferrocement.org/
