The teeny homes, which start at just 65 square feet are kitted out with fully functioning kitchens, bathrooms complete with composting toilets and sleeping areas.
Some models even come on wheels.
As well as being environmentally friendly the homes are affordable for people on meagre incomes.
As the debt problem in the U.S. reaches tipping point Mr Shafer, who lives in one of his houses in Sebastapol, California, says that less can be more.
'People are starting to get a clue I think,' he said.
'People are starting to understand that excess is not necessarily a luxury. It can be a burden, a liability. People are living in 4,000 and 6,000 square foot debtors prisons.'
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